It's not Temu. Same thing's been happening to me and I don't have Temu. In fact, it's been happening for as long as I can remember, just on my phone, and occasionally my tablet. Not every page, and usually there would be a rash of them, then it would let up for a little, then come back.
CW4D has it right. When it comes up, I just swipe left to right (back) and I get returned to the Dis.
Adblockers on the computers, so it doesn't happen there.