Not that I'm aware of. We've had people post some really, really long comments.

What happens when you try?

It opens nothing. I mean - i post comment, page ( for example gelbooru.com/index.php?pa...772&tags=hirasawa_yui ) seems like posting your comment, but after that it is the same page with 0 comments(in case my comment was meant to be first there). Like some spam filter silently eat all I've just wrote (I saw this feature on certain other websites/forums/comment area), without warning. 1-2 sentences comments are ok though(as in link above).

I wish I could make a test of this and post different comments with different content and length, but there is no way to delete my own comments, so just let it be... I am not much of a talkative type anyways.

The only thing I can think of is that you may have used a word blocked by our word filter.

I can't create new forum threads (but I can create replies to unlocked threads, obviously), and despite toggling the "display all content" option, it never seems to work (images still blurry, searches appear to be censored, and I can't edit tags (for "censored" content) any more).

All ad blocking/script blocking etc. disabled except for browser defaults (no cross-site tracking and such). Tried multiple browsers, multiple devices, and two different networks (all with my account logged in, mind you). Tried clearing cookies and caches. Tried removing blacklist. Even tried logging out.
Nothing works.

So what gives? Is my account shadowbanned or, more likely, my IP address (range) banned or something like that? I spend a lot of time on this site tagging images that need tags, but now I can't do that...

Apparently can't edit my posts either (only on Safari - sorry, would have edited the previous one if I realised sooner), but I managed to fix tag editing on Safari (somehow - I just logged out and in again, for about the fourth or fifth time, and then suddenly it was working). Still broken on other browsers (Chromium-based). So confusing. No idea what the issue is.

Everything else is still borked though, and when I try to reply here on Safari, I get redirected to the front page. Works on Chromium. Weird discrepancies...

We don't shadow-ban. If you (or your IP) were banned you would not be able to log in at all.

Are cookies enabled? Beyond that you'll need an admin to help you. The Gelbooru Discord Help page might be faster.

Yep, cookies are enabled. Good to know more specifics on bans - thanks.
Edit button now appears in Safari. Other problems still persist though. It's not a huge deal, I guess. More just annoying than anything.
Will have to try my PC once I get my motherboard RMA back. Tried on macOS and Android, but frankly, I think this Mac is starting to become an unreliable liability.

How do you quote a user?

Click on quote in the upper-right corner of their comment.

I don't see it. ;_;