People are commenting as if it were your own work colleagues, who might know this is not the norm for you, asking for info.
It’s not.
It’s random people who encounter the OP as a customer in their place of work.
Speaking as a person with a permanent visible disability that is presumed to be an injury, and therefore open season for intrusive presumption by random strangers, i get how annoying this is.
UK culture deems it fine, or even actively polite, to ask a total stranger “what have you done to yourself” if they appear “injured”.
I’m not injured.
I haven’t “done” anything to myself - and unless you live with something like this you have no fucking idea how incredibly rude and hurtful it is to be asked that question, year in year out, for something you didn’t “do” to yourself and that causes serious chronic pain, all day and all night, for life.
I have a lifelong visible disability, and zero patience with intrusive insulting questions from strangers, acquaintances, passers by or shop staff.
Rant over.
On a more positive note OP, a well practiced deflection is the fastest way to close it down and move things along without somehow winding up judged as the rude one.
“Long story, not interesting” roll straight into a question or prompt they have to answer.
If they persist after that, a firm stare, “I don’t want to talk about it” and roll straight on again.
If they still go on, they’re indisputably being rude now, and you can tell them to stop, or to fuck off as the mood takes you.