I'll have to take a look at the code again to see if anything is wrong with it. For the protection report, we do not care the hour the tracker is recorded, only the day. Because of this, we record all days in the database as if they are in UTC at exactly noon, the theory is that at noon in UTC most places on earth are in the same day. Unfortunately this does not account for any daylight savings time changes and it is never the same day everywhere in the world. There is always an exception in the timezones directly to the west of the date line. We should rethink this.
The other thing a user may notice, is that the trackers get added to the database when the page closes, not at the moment the trackers are being blocked. This is because new trackers may be blocked as the user spends time on the page. So if a user opens a page yesterday, but closes it today it will be recorded as today.