Mesh Noise Glitch in X-Ray Mode Blender Version: 2.91 (also 2.83) 
GPU: Radeon RX 590 (with and without updated drivers)
Edit:
I stumbled upon the problem in another context which lead me to a way to recreate the glitch in a clean file:

Open Default File (named General)
Go to the material of the default cube (in Solid Mode)
Under Viewport Display go to Color and set the Alpha to anything else than 1
Add a new material

This creates the glitchy mesh seen in the image below.


Original Problem:
My viewport shows weird noise when I toggle x-ray mode only in solid view. 
I had In Front (under Object Properties&gt;Viewport Display) enabled for my mesh and after a lot of searching I found out that I can toggle the glitch by disabling that.
I cannot seem to recreate the glitch in a clean file though and I'm a bit afraid that something is broken in my file.
Things I tried before the &quot;In Front&quot; toggling:

deleting all vertex groups, materials, modifiers and all other objects in the file
switched from smooth to flat shading
cleared all marked edges
disabled auto-smooth
disabled all addons (and later used a clean install)

Changing the workspace resets the view but the glitch returns on toggling x-ray view.
At least when I export the mesh as an FBX file that seems to be glitch-free. Though that way I lose all my vertex groups.
Any ideas what is happening here?
The glitch appears to be a driver issue with Radeon GPUs, especially with recent Blender versions. It is, as of yet, unresolved.
Link to the Bug Ticket:
https://developer.blender.org/T83022