In my opinion, fraud prevention is, of all reasons to retain data, the least important. This example of dating app behaviour is easily detected with simple heuristics, and leads to far more important information than fraud could ever be.
in this case I really meant that the act of deleting and reinstalling the app is the fraudulent act, although it is not what most people would consider fraud (i.e. financial fraud) it would normally fall under "trust and safety" I guess.
I heard that EU food delivery apps was frauded this way: customer installs app, get hefty first delivery discount, asks to delete their data due to GDPR, rinse. repeat. They figured that out by keeping a hash of their phone number for some time like 3 months and not giving a discount to those numbers.
