I found that when I use today's timestamp or yesterday's timestamp, I get the same data. For example:
https://api.torn.com/user/2901842?selections=personalstats&key= & timestamp=1735611065&stat=xantaken
https://api.torn.com/user/2901842?selections=personalstats&key= &stat=xantaken
we all get
"personalstats":{"xantaken":2043}}