Here is the general guideline for when you need to use a sarcasm tag:

If your comment could be plausibly stated as genuine instead of sarcastic by someone reading your comment, then your comment needs to be denoted as sarcastic.

This is to say, if you're in a group chat with your friends and all of them are like-minded, then typing something sarcastic probably doesn't need a sarcasm tag, since no one in the group chat would plausibly type that comment as genuine. However, if you're in a more-or-less public forum and you type something sarcastically, it becomes far more likely that your comment could be typed out as a genuine stance instead of a sarcastic one, and therefore it is wise to make it clear that you are not one of those people.

It is possible, even in 2023, to craft a comment that is so obviously sarcastic that it does not need a sarcasm tag even when posted in public, but this is pretty rare-- most people are typing stuff that could easily be typed genuinely.