I'm not sure how long this has been the case, but it seems like all series tagged yaoi or yuri have been filtered to have the "adult content" blank thunbnail in the listings.

Yes, I know that yaoi and yuri denote sexual content, but most of the covers are just two people standing next to each other. Moreover, the ecchi and smut tags still display their covers fine, even the borderline-H ones.

So this seems less about sexual content and more about preventing anyone from accidentally seeing something gay. Can anyone explain the reasoning behind this change?

It has been like this for years, maybe decades. It only applies if you're not logged in

A just ruler amongst tyrants