Why is the counted screen time much longer than I have used?

I am trying to limit my usage of certain websites, but I have found this challenging on macOS. The screen time tracked is often much longer than my actual usage, and some of the apps or websites being counted are not even installed. (I have already **turned off** device sharing to avoid complications.) For example, I do not have YouTube app installed, yet it is counted for 4 hours 18 minutes: Also zhihu.com, which I only used for a few minutes, is counted to have been used for as long as Safari is used: I went through all the tabs on Safari, including all the tab groups, but I still can not find where zhihu.com might be secretly open. I also tried rebooting my laptop, but it did not resolve the issue. - macOS version: 10.15.7 - Safari version: 15.6.1 Any thoughts would be greatly appreciated! ---------- BTW, I saw this answer for iOS, which did not solve the problem either.