A lot of Polaris users suffer from black screens and often raising the Power Limit slider in Radeon Settings will help this.
However it bothers me that this wasn't happening until you changed drivers.
In Radeon Settings go to the performance tab, tuning tab, and near the bottom find the "Power Limit" Slider.
Move that slider to the right to its maximum of 50.
https://community.amd.com/t5/blogs/performance-tuning-with-radeon-software-adrenalin-2020-edition/ba...
If that doesn't help then do the following:
I would suggest trying to install the drivers from scratch again as sometimes things just corrupt.
Have the driver downloaded from AMD
Download and run DDU from wagnardsoft dot com from safe mode with Internet unplugged or wifi off.
Restart with Internet still disconnected.
Install the AMD driver but don't pick express install. Choose the"Factory Reset" option.
See if that helps.
I that doesn't help repeat the same process above but install a previous driver that worked for you and report the issue to AMD:
In Radeon Settings there is a Bug Report tool too you can submit the issue or
You can contact AMD support here: https://www.amd.com/en/support/contact-email-form
Good Luck!