The simplest explanation is that OP doesn’t have good opsec, and got a few tracking cookies after deleting cookies, before setting up their proxy/VPN. Then, on the VPN, the advertiser recognized their VPN IP address, and chose to exclude that from generating location data, deferring instead to the location indicated in their existing tracking cookies.
Privacy is hard. The system is rigged against privacy. You have to do everything perfectly, because one simple mistake could leak your IP address.
Rednote is a proprietary app-only non-federated social network subject to the censorship of a totalitarian government, China. It blocks discussion of 6/4, Free Hong Kong, Uyghur genocide, and probably all the other stuff normally censored in China. I encourage any skeptics to visit the Chinese Wikipedia from within China.