Hey, I found a working solution
After update macOS to the 10.15.6 I noticed that Xcode throws info that is not enough space on disk to update app, so I tried to run old Xcode and I noticed a popup about missing requirements, after click "install" the problem about updating Xcode in AppStore gone.
There was no needed steps to uninstall Xcode so I'm happy of that :)
I hope that this will help you too