This is one of the easiest ways to lose your bitcoin, storing crypto on any third party app/site is always a bad idea, remember you don't hold the private key to that coinbase account, your account could get hacked or even permanently banned by coinbase, I have seen some cases where someone stored a huge amount of bitcoin and overnight coinbase decided to put his account under review, meaning he can't gain access into his coinbase account and his bitcoin is locked till they decide to open it, to be safe always make use of a hardware wallet like ledger to store your bitcoin or use a regular mobile wallet like trust wallet, keep your private keys/seed phrase safe don't share it with anyone.