Github: new size is 460px

[FliegendeWurst]

Larger images are scaled down. You can verify the new size by downloading a profile picture, it will be 460x460 pixels large.

[chuckreynolds]

They may do that for specific display you were on but their docs still say 500x500:

Note: Your profile picture should be a PNG, JPG, or GIF file, and it must be less than 1 MB in size and smaller than 3000 by 3000 pixels. For the best quality rendering, we recommend keeping the image at about 500 by 500 pixels.

src: https://docs.github.com/en/account-and-profile/setting-up-and-managing-your-github-profile/customizing-your-profile/personalizing-your-profile

[FliegendeWurst]

Yes, I saw that bit in the documentation.
It's not just my display, Github only serves 460 x 460 avatars: https://avatars.githubusercontent.com/u/46185
You can replace 46185 by any other user id, I think all of them will return at most a 460 x 460 pixel image if there is an avatar at all.