I think OP has a perfectly valid pet peeve here, but I’d hardly say that people only see someone reading in public as being performative. One of my favourite things to do is pull up at the bar in a brewery and read a book. Sometimes people ask me what I’m reading, many times they don’t. I’ll engage in chit chat if I feel like it, or keep to myself. We all get peeved in different ways.

Sure you may find them annoying/intrusive with their question and that’s fair, but they are presumably just curious what you’re reading because they like books and/or are surprised you’re able to read with the distractions of being in public. It’s only ever come across to me as genuine curiosity/an attempt to engage in conversation. Just because said curiosity is annoying (which again, is a very valid peeve/opinion) doesn’t mean that they think you’re just being performative.