Two issues.

First of all a lot of websites show times in your current timezone. Beehaw for example says you wrote your post “2 days ago”. Depending what timezone my browser is in, that could display 3 days or 1 day. When I hover over it, it shows the exact date/time in my timezone. Which is handy.

Second it doesn’t actually achieve the intended goal. Even if you use a VPN chances are you’ve set it to give you a public IP address close to you to have good performance. And if your IP address is in Proton’s London datacentre but your timezone is UTC+0 when everyone else is UTC+1… well you stand out like a single black sheep in a flock of white ones and ad networks are absolutely fingerprinting you with that.