Are you signed up with Firefox Monitor? Firefox Monitor searches for your email in publicly-available data breaches back to 2007.

Here's an article with more:

Firefox Monitor - Frequently asked questions https://support.mozilla.org/en-US/kb/firefox-monitor-faq

I have not signed up with FF Monitor. I rely on the same software I have since 1985.

Just to make sure:

Where do you see these logins ?

Is that in the Firefox Password Manager or is this part of a notification that is about a breach on a website ?

Cor-El - I go to a web site the has a log-in box. I click on the user name box and firefox throws up accounts that were deleted years ago. Perhaps FF is grabbing info directly from the web site?

So this is about Firefox showing possible login suggestions. The first three are for this website, the others are other (Google) domains that are included in Firefox 71.

• about:config -> signon.includeOtherSubdomainsInLookup

You may not be using these Google accounts, but it looks that they are still stored. Firefox gets this information from the Password Manager, so you should see them there listed if you filter for google.com.

• "3-bar" Firefox menu button -> Logins and Passwords

Interesting. Prior to FF71 the last three never showed up so FF&1 must have somehow dug out old key4. db and logins. json files.