Do you have any examples?

Well now I’m going to, jk.

Actually no, the hexbear comment is clearly bad in my opinion, regardless of if it was sarcasm.

Ironically, I’m of German descent, but whichever heritage someone is in my opinion would be the same.

No clue, could be either. It’s text on a screen and the only emotion present, is the one you decide to apply to it.

Ask them if it was a joke or not to be sure, and if you have to ask, it’s because it might not be.

We all know words can’t really express sarcasm or other underlying feelings or meanings very clearly. Without a /s your only able to assume if the they did or didn’t actually mean that.