Updating avatars on the web at large is a fucken PITA. Gravatar.com tries its best but it depends on individual services implementing its API and a lot of them simply refuse, choosing instead to go with facebook/instagram.
The other thing is using the
email@example.com format. A lot of services won’t let you sign up with an email that looks like that but once you’re up you can usually change your email. I’m not sure if gravatar.com is able to track this sort of thing but as of 2019-12-29_00-03 it certainly doesn’t look like it.