The page footer for itch.io presents the defunct Twitter icon on nearly every page.
I recommend its removal to be replaced with a Mastodon icon and link.
Alternate suggestion: Remove the site’s neglected social media link menu fully.
Contact info for Itch.io is linked in the footer. That’s much more important.
For promotion, individual creators can link to wherever that’s allowed. (X-Twitter suppresses external links and artist accounts.)