A web page that tells you what your browser gave away the moment you arrived. No login, no form, no permission. Most pages do this. None of them tell you.
Assuming it’s tz database timezones then they can be relatively specific. Since the slices are based around laws governing current time, there’s hundreds of slices rather than just a couple dozen. https://en.wikipedia.org/wiki/List_of_tz_database_time_zones Alongside things like keyboard downloaded it means you can be uniquely fingerprinted (or close to unique) pretty easily, which means they can then associate all sorts of other information with you
Assuming it’s tz database timezones then they can be relatively specific. Since the slices are based around laws governing current time, there’s hundreds of slices rather than just a couple dozen. https://en.wikipedia.org/wiki/List_of_tz_database_time_zones Alongside things like keyboard downloaded it means you can be uniquely fingerprinted (or close to unique) pretty easily, which means they can then associate all sorts of other information with you