Check out https://codeberg.org/Kbin/kbin-core/issues/1019 to see if it's similar to what other people have posted about recently: tl;dr blocking domains appears to filter out posts / comments even when those domains are not involved in the post. I'll repost what I put in one of the threads:
If posts are disappearing when you're logged in but not when logged out, it should be something like that: either a language filter, federation turned off, or a blocked community you might not expect filtering it out. You can double check by unblocking domains/magazines to see if any of them return comments, though that might be troublesome with many blocked.