Tested the issue on reported chrome version #70.0.3538.77 using Mac OS 10.13.6 by following below steps.

Steps;
=====
1.Launched chrome.
2.Navigated to "duolingo.com".
3.Signed into the account.
4.Navigated to Settings-> Password, entered current password.
5.Right clicked on new password text field but unable to find the auto-generated password.

Attached screencast for reference.
@reporter: Could you please review attached screencast and let us know if anything is being missed here.
Thanks.!

Deleted: 900096.mp4 1016 KB

	900096.mp4 1016 KB View Download

That's a similar problem but not quite the same.

Instead of logging in, hit "I forgot my password" and follow the link they will send you in an email. That gets you to the Reset Password screen from my screenshots.

The problem you show in the screencast seems like Duolingo's fault for not offering "new password" + "new password confirm" boxes.

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Able to reproduce the issue on reported chrome version #70.0.3538.77 and latest chrome #72.0.3297.0 using Windows 10, Mac 10.13.6 and Ubuntu 17.10 by following steps as per comment #4.

The behavior is seen from M-64 builds(#64.0.3572.0)  we have seen "Generate password" by giving the right click on the password field. Considering this is non-regression issue and marking it as untriaged. Requesting someone from the dev team to look into the issue.
Note: Until chrome version #64.0.3571.0 the chrome crashes after selecting generate password (from M-60 to M-63 the generate password is not seen by default).
Thanks.!

Thanks for reporting and verifying that the issue is reproducible.