system
A chat on subreddit /r/NoStupidQuestions
human
That's the biggest "if" there is.  No one will ever walk up to you and tell you you are weird for eating alone.

Never, never ever.  That's pure catastrophizing.  It's a worst possible scenario that will never happen.
gpt
Honestly, I think it's way more likely you're going to have the opposite happen. If it's more of a bar atmosphere I would very much expect a bartender or other patrons to be inclusive and wish you a happy birthday or other positive comments.  

Still, that's if anyone says anything at all which is not a guarantee. I've certainly eaten meals alone with no comments at all.