The 2020 drivers are buggy as heck. Dont use them yet. Revert back to 2019 drivers if you can.
A few other things you could try if you really dont want to do this is:
Clean uninstall (in safe mode if you can) via AMD uninstaller (dont use DDU), then reinstall w/ factory reset.
Repeat this 3-4 times if it doesn't work.
IF crashes still happen then there im not sure what to say. 5700 XT has a known hardware acceleration issue. Not sure if Vega could have the same issue or not. YOu could try disabling HW acceleration if you'd like.