I've had this issue for a while, my preview goes from normal to this for seemingly no reason. To be clear, it doesn't always look like this, but anytime I try to interact with the window, i.e. drawing masks it looks like this. I have cleaned my cache, and just updated my graphics drivers.
This is my graphics card, I recently updated the drivers. I have tried restarting the computer but it's still an issue. Draft 3D: Available Texture Memory: 3204.00 MB Graphics Card Vendor: NVIDIA Device: NVIDIA GeForce RTX 2070 SUPER Version: 11.700000 Total Memory: 8.00 GB