Screen time not adding up

I'm confused by how Screen Time is reporting total numbers. The total reported is always more than if I add up the individual categories or the "apps&websites" numbers, sometimes significantly.

Is this time spent on the home screen, or are there other activities that are not categorized correctly?

For example, today I have 1:59 total screen time so far, made up of 11min/10min/8min of the categories shown in the graph, and 1:07 in the settings app (which doesn't seem to be counted in any category). That makes 1:36, which is 23min off from 1:59. Interestingly, 23min corresponds exactly to the reported Safari usage. But as far as I understand, Safari is reported in parallel in webpages, i.e., if you surf apple.com for 5 min, you will get 5min for apple.com as well as 5min for Safari.

Any ideas?