1) Go to https://www.petrobraspremmia.com.br/register
2) Right click on password field
3) Select "Generate password" and confirm it

Observe that the generated password is not filled into the field.

Assigning P3 as I have not seen many sites with this behavior.

Captured password manager logs are listed below. Logs are cleared and no longer captured when all password-manager-internals pages are closed.
Message: PasswordAutofillAgent::DidStartProvisionalLoad 
Message: PasswordAutofillAgent::DidStartProvisionalLoad 
Message: PasswordAutofillAgent::DidStartProvisionalLoad 
The new state of the UI: 0
Message: PasswordAutofillAgent::DidStartProvisionalLoad 
Message: |frame| is not the main frame 
Message: PasswordAutofillAgent::SendPasswordForms 
only_visible: false
Security origin: https://staticxx.facebook.com/ 
Number of all forms: 0
Message: Generation invalid PasswordForm 
Message: PasswordAutofillAgent::SendPasswordForms 
only_visible: true
Security origin: https://staticxx.facebook.com/ 
Number of all forms: 0
Some control elements not associated to a form element are visible: false
Message: PasswordManager::CreatePendingLoginManagers 
SSL errors present: false
IsPasswordManagementEnabledForCurrentPage: true
Number of pending login managers (before): 0
Number of pending login managers (after): 0
Message: PasswordManager::OnPasswordFormsRendered 
Message: PasswordManager::CanProvisionalManagerSave 
Message: No provisional save manager 
Message: Generation invalid PasswordForm 
Message: PasswordAutofillAgent::SendPasswordForms 
only_visible: false
Security origin: https://www.petrobraspremmia.com.br/ 
Number of all forms: 5
Form is a password form: {
Action : https://www.petrobraspremmia.com.br/ ,
New password element : ,
Origin : https://www.petrobraspremmia.com.br/ ,
PSL match : false,
Password element : j_password ,
Password generated : false,
Scheme : HTML ,
Signon realm : https://www.petrobraspremmia.com.br/ ,
Times used : 0,
Username element : j_username 
}
Form is a password form: {
Action : https://www.petrobraspremmia.com.br/ ,
New password element : checkPwd ,
Origin : https://www.petrobraspremmia.com.br/ ,
PSL match : false,
Password element : pwd ,
Password generated : false,
Scheme : HTML ,
Signon realm : https://www.petrobraspremmia.com.br/ ,
Times used : 0,
Username element : cpf 
}
Message: PasswordManager::CreatePendingLoginManagers 
SSL errors present: false
IsPasswordManagementEnabledForCurrentPage: true
Number of pending login managers (before): 0
Adding manager for form: {
Signature of form: 12357640629863003286
Signon realm: https://www.petrobraspremmia.com.br/
Origin: https://www.petrobraspremmia.com.br/
Action: https://www.petrobraspremmia.com.br/
Form name: topFormLogin
Form fields: 
j_username: 94183295, type=text
j_password: 1796512061, type=password, autocomplete=off
}
Message: FormFetcherImpl::Fetch 
FormFetcherImpl::state_: 1
Adding manager for form: {
Signature of form: 2483062518304501963
Signon realm: https://www.petrobraspremmia.com.br/
Origin: https://www.petrobraspremmia.com.br/
Action: https://www.petrobraspremmia.com.br/
Form name: registerForm
Form fields: 
cpf: 3696290292, type=text
firstName: 1855613035, type=text
lastName: 4163345999, type=text
birthday: 657895188, type=text
gender: 570340743, type=radio
gender: 570340743, type=radio
email: 420638584, type=text
checkEmail: 3496246942, type=text
cellphone: 1834098906, type=text
pwd: 2597353482, type=password, autocomplete=off
checkPwd: 2653144671, type=password, autocomplete=off
subscribeEmail: 2900521752, type=checkbox
subscribeSMS: 2144911419, type=checkbox
agreement: 3805914131, type=checkbox
}
Message: FormFetcherImpl::Fetch 
FormFetcherImpl::state_: 1
Number of pending login managers (after): 2
Message: Generation invalid PasswordForm 
Message: Generation invalid PasswordForm 
Message: Generation invalid PasswordForm 
Message: Generation invalid PasswordForm 
Generation possible account creation forms: 2
Message: Generation: no non-blacklisted confirmation 
Message: Generation: no non-blacklisted confirmation 
SSL errors present: false
IsPasswordManagementEnabledForCurrentPage: true
Server predictions: {
Signature of form: 2483062518304501963
Origin: https://www.petrobraspremmia.com.br/
Action: https://www.petrobraspremmia.com.br/
Form fields: 
cpf: 3696290292, type=text, SERVER_PREDICTION: USERNAME
firstName: 1855613035, type=text, SERVER_PREDICTION: NAME_FIRST
lastName: 4163345999, type=text, SERVER_PREDICTION: NAME_LAST
birthday: 657895188, type=text
gender: 570340743, type=radio
gender: 570340743, type=radio
email: 420638584, type=text, SERVER_PREDICTION: EMAIL_ADDRESS
checkEmail: 3496246942, type=text, SERVER_PREDICTION: EMAIL_ADDRESS
cellphone: 1834098906, type=text, SERVER_PREDICTION: PHONE_HOME_CITY_AND_NUMBER
pwd: 2597353482, type=password, autocomplete=off, SERVER_PREDICTION: ACCOUNT_CREATION_PASSWORD
checkPwd: 2653144671, type=password, autocomplete=off, SERVER_PREDICTION: CONFIRMATION_PASSWORD
subscribeEmail: 2900521752, type=checkbox
subscribeSMS: 2144911419, type=checkbox
agreement: 3805914131, type=checkbox
}
Message: Generation: no non-blacklisted confirmation 
Message: Generation: no non-blacklisted confirmation 
Message: FormFetcherImpl::OnGetPasswordStoreResults 
Number of results from the password store: 0
Message: FormFetcherImpl::OnGetPasswordStoreResults 
Number of results from the password store: 0
Message: PasswordAutofillAgent::SendPasswordForms 
only_visible: false
Security origin: https://www.petrobraspremmia.com.br/ 
Message: Webpage is empty 
Message: Generation invalid PasswordForm 
Message: PasswordAutofillAgent::SendPasswordForms 
only_visible: true
Security origin: https://www.petrobraspremmia.com.br/ 
Number of all forms: 5
Form found on page: {
Action : ,
Form name or ID : search_form_SearchBox 
}
Form is visible: true
Form found on page: {
Action : ,
Form name or ID : 
}
Form is visible: true
Form is a password form: {
Action : https://www.petrobraspremmia.com.br/ ,
New password element : ,
Origin : https://www.petrobraspremmia.com.br/ ,
PSL match : false,
Password element : j_password ,
Password generated : false,
Scheme : HTML ,
Signon realm : https://www.petrobraspremmia.com.br/ ,
Times used : 0,
Username element : j_username 
}
Form found on page: {
Action : ,
Form name or ID : search_form_SearchBox 
}
Form is visible: false
Form found on page: {
Action : ,
Form name or ID : 
}
Form is visible: true
Form is a password form: {
Action : https://www.petrobraspremmia.com.br/ ,
New password element : checkPwd ,
Origin : https://www.petrobraspremmia.com.br/ ,
PSL match : false,
Password element : pwd ,
Password generated : false,
Scheme : HTML ,
Signon realm : https://www.petrobraspremmia.com.br/ ,
Times used : 0,
Username element : cpf 
}
Form found on page: {
Action : ,
Form name or ID : accessiblityForm 
}
Form is visible: false
Some control elements not associated to a form element are visible: false
Message: PasswordManager::CreatePendingLoginManagers 
SSL errors present: false
IsPasswordManagementEnabledForCurrentPage: true
Number of pending login managers (before): 2
Number of pending login managers (after): 2
Message: PasswordManager::OnPasswordFormsRendered 
Message: PasswordManager::CanProvisionalManagerSave 
Message: No provisional save manager 
Message: Generation invalid PasswordForm 
Message: Generation invalid PasswordForm 
Message: Generation invalid PasswordForm 
Message: Generation invalid PasswordForm 
Generation possible account creation forms: 4
Message: Generation: no non-blacklisted confirmation 
Message: Generation: no non-blacklisted confirmation 
Message: Generation: no non-blacklisted confirmation 
Message: Generation: no non-blacklisted confirmation 
Message: PasswordFormManager::ProcessMatches 
SSL errors present: false
IsPasswordManagementEnabledForCurrentPage: true
Message: Generation: no server signal 
Message: Generation: eligible form found 
Message: Show generation popup 
Message: PasswordFormManager::ProcessMatches 
SSL errors present: false
IsPasswordManagementEnabledForCurrentPage: true
Message: Generation: account creation form already found 
Message: Show generation popup 
Message: Generated password accepted