Adding more details about the feature:

Today, Autocomplete saves and shows text that was submitted by the user only once. This might be useful, but there are a lot of cases where we serve suggestions that we know won’t be useful for the user (e.g. Captchas, tracking numbers). With the Autocomplete Probation feature, we will be showing the users only inputs that were submitted more than once.

 Issue 922445  has been merged into this issue.