The two biggest anti-features for me are the star system and the contribution activity green tile thing that appears on a user's page. To me personally, both of these systems subtly frame one's commit frequency and stars as a measure of how good they are as a programmer.
I believe these "features" turn the site into a pseudo-social media outlet and allow vanity to creep into process by which communities develop software. It is something that I noticed quite a lot during my (recent) years in undergrad: where many individuals directly equated stars with software quality (in there own projects or the projects of others). I know that those features in particular are only part of the problem (if the problem does truly exist), but they personally made me uncomfortable with the platform and are one of the primary reasons I left GitHub a few years ago.
That's just my opinion though, so take it with a grain of salt.
I've been a sourcehut user for about half a year now and I have to say that it has been a breath of fresh air for me. I have used GitHub and GitLab for years, and detest working with either. I know that both companies have a lot of smart people behind them, but both GitHub and GitLab are horrendously slow to use on my internet connection and packed to the brim with what I could consider anti-features. With sourcehut I finally have a code hosting solution that lets me focus on being productive.
I bind my CAPSLOCK to ECAPE that way instead of the escape key killing my hand my left pinky finger can just naturally get me out of insert mode by hitting CAPSLOCK.
I believe these "features" turn the site into a pseudo-social media outlet and allow vanity to creep into process by which communities develop software. It is something that I noticed quite a lot during my (recent) years in undergrad: where many individuals directly equated stars with software quality (in there own projects or the projects of others). I know that those features in particular are only part of the problem (if the problem does truly exist), but they personally made me uncomfortable with the platform and are one of the primary reasons I left GitHub a few years ago.
That's just my opinion though, so take it with a grain of salt.