So I have an issue with my Bitcoin being sent to my cash app it got rejected then it got sent back and now is stuck with a low fee but I have no private key or anything like that to bump it and it's just been sitting there I don't know what to do the address that it was being sent back to is from a game so there's no private key for that either
If you have used a service provider and the funds have been returned there, you have to get in touch with the service provider and ask then to recover the funds for you as they have the private key. This is likely to cost a fee on top of the network fee, if they are able to facilitate. Most services will ask for an unreasonable fee though if you argue about it and claim only for them to take the network fee, they will do exactly that. This is considering considering their support is good and it's a completely legitimate service.
In the future, use a wallet. Sparrow, electrum, etc. All are good choices for quick. Easy set-up wallets.