late to this discussion, but in terms of using Google Analytics, you can whitelist specific domains if someone is copying your UA code and sending your instance

late to this discussion, but in terms of using Google Analytics, you can whitelist specific domains if someone is copying your UA code and sending your instance data. Most implementations are set up this way from the start so you don't even need to notice someone is attempting to poison your data. One of the reasons this is done is to generate referrer spam, which is a really niche way to get the analysts who are looking at the data in GA to see their ads. I'm sure there are other reasons folks do this, perhaps there's a UA- code factor into PageRank/Google rankings that spammers picked up on, I can think of a lot of other creative reasons. That said, it's pretty curious that there are a lot of sites using it, you might do well to see if you can intercept some mobile app data to see if any other apps are also using the UA tag of TikTok. There are other things you could look at in terms of how they implement the actual tracking in GA, if the tracking calls look pretty similar but aren't just a carbon copy, it could be more intentional.