Grindr question

I don't keep a pic up on my profile, thanks to an unknown creep who keeps catfishing some super hateful stuff.That's mostly irrelevant to my question, just pointing out why I don't use a pic up front, only when I message people.However lately, several different guys I've chatted with, one to the point of preparing a meet, have begun replying with "?" when I greet them. As if we had not spoken or something. At first I thought, maybe they cleared the chat or reinstalled the app and don't immediately recognize me.But it's happened with so many guys that I'm wondering if "?" is a new way to throw shade or ghost people- just act like you don't even know them.