$450 for an RX 5700 XT is quite expensive, esp. Excl. Tax.
The Reference RX 5700 XT were £380 and are still selling for about that... and that's with VAT.
No joke, it would've been cheaper for you to purchase from the UK and Import (which P&P costs approx. $25) than have bought it locally.
With that said... it's curious that you're still experiencing Black/Green Screen.
I've only experienced a single case of it since upgrading to 20.4.1 and even then, I have a feeling it was more my own fault as it was with a Development Build of my in-house Engine that I was testing some Vulkan 1.2 Extensions with.
Since I've also switched from Microsoft Edge (Edge "Classic") to Edge Chrome for watching Online Videos., I've also not had any Kernel/Driver Crashes that Hard Crash the System.
I'm hoping at some point they do fix whatever issue there is between the Edge Web Engine and the Drivers, as I still prefer using it as my default browser over this Chrome-based crap.
•
Now as a keynote, when you begin the Driver Installation it will ask you if you want to enable Factory Reset (which means a CLEAN Driver Installation) ... you should ALWAYS do this with Graphics Drivers, but AMD Drivers esp. tend to retain legacy issues when you don't clean install updates.
I don't know why AMD doesn't force that as the Default approach, given their track record; and would resolve a lot of common issues that less technically minded users have.
If it does keep happening then in Radeon Settings, select the Cog Icon (Top-Right) and System Tab.
At the bottom there is a "Report Issues Online"
This will take you to an issue report form... fill it out with as much detail as you can (it'll walk you through other information it wants you to collect).
Do this EACH TIME the issue occurs.
This will help the Software Engineers track down the specific issue.
I would also strongly suggest... if you've upgraded from NVIDIA, then use the Driver DDU App (or better still, perform a Windows Clean Reset; which can be found at Settings > Recovery > Reset this PC) to ensure that you've cleaned Windows 10 up.
Again Windows 10 cumulative updates might resolve some issues, but due to how Microsoft no longer has a QA Team and doesn't perform these Updates "Cleanly" it means that you can actually have some legacy issues from previous Windows 10 bugs present after a Major Release Update (such-as 1909 / Spring Creators Update 2020 that occurred not to long back) that tend to adversely affect AMD more than Intel/NVIDIA.
•
While I know this all might be a pain., remember these are general tips that ideally you should've been doing anyway not simply because you have AMD Hardware now.
Those two simple approaches typically resolve a good majority of persistent issues people have.