Definitely, though some subs have more of these ‘filters’ in place than others. Worldnews was particularly egregious; innocuous links would have a 50/50 chance of getting a comment shadowbanned, leading to a nosedrive in the quality of discourse as no one was willing to go through that gauntlet to provide sources (or just didn’t know their posts were getting censored).
Of course, any mention of ‘shadowban’ or related words is also an instant shadowban. SOP pretty quickly became to try to open your comment in an incog window to see if it had been turned invisible to everyone but you or not.
Similar thing happens with youtube comments, and probably on a plethora of other platforms as well. Between that and bots and other trickery, more and more of the conversations we see on the internet are manipulated and no longer truly real.
Erroring out is just being broken, but accepting and then deleting comments is a filter that is shadow banning your comment (so that you can’t tell it’s been removed and try to re-post it by circumventing the filter).