I recently attempted to log in to a credit card processing site with the username and password stored in Firefox. Firefox auto-supplied just my username, and when I tabbed to the password field to enter that info, the username disappeared. If I tried to enter the password and return to the username field, the password disappeared. The site naturally read this as an incorrect login attempt. Tech support for the site suggested this was a browser issue and recommended I switch to another browser, and they advised clearing the cookies and cache before each time I log into their site. Sort of defeats one benefit of having a computer.

I'm using version 86.0 of Firefox released 2/23/21 -- my last successful use of the site was 2/15/21 so I'm wondering if anybody else has seen this happen in version 86.0?