I only got a couple contradictory responses last time I polled people. I was expecting none, though, so it left me unsure. I tweeted you a copy of my test template and the results saved by another pixel artist. Maybe you can poll your own followers.
Pedro Medeiros posts animated gif tutorials on Twitter. The raw GIFs on his Patreon are 512x512, but lately, they seem to be squashed to display at 506x506 on Twitter, even though the actual MP4 file that's playing is 512x512.
Compare his Twitter MP4s with the Patreon GIFs and see if it's the same for you. twitter.com/saint11www.patreon.com/saint11
Personally, I wish they'd just release a formatting doc for artists, so we wouldn't need to test for changes over time.