I've provided it to hotel staff, Airbnb hosts, condo security, car rental places, airline staff, and more over the years. They all make copies of it digitally and physically so it's floating around out there in lots of places.

Next time I get a passport it will change anyways so I'm not sure I see the big deal even if it was a unique, never changing number.

And with the new COVID stuff/vaccinations, it's being shared more often even if you don't travel.