You can choose to update the history stack or not. For example, this page uses the History API to update the url without changing the browser history stack:

https://wakatime.com/pricing

Click the toggle to show yearly pricing and the url is updated, but you can still press back to go to whatever previous page you visited.

Then, this page DOES update the history stack when the url changes: https://wakatime.com/dashboard

Click the date range and select a new range, notice the url changes but also you can press back to go to your previous date range.

It breaks the expectations user have about browser. It is very snaky way to try to make a browser what it is not, all in the name of making SPA just to make a trend. It is one of thing most annoying about the IT industry, that it is a more about fashion then about tech.

I've never seen that done, sounds like a bug in the website because there's not reason to do that. It's also an easy fix: close the tab and don't use websites that do that.