I have the problem as unexpected in Unexpected image rendering behavior in the Library module | Lightroom Classic CC described. I have the steps 1 to 4 the only one tried, what helps is solution 3 disable Direct2D. The photos appear normal again after restarting Lightroom. Does disabling Direct2D negative performance?
Lightroom classic version: 7.3 
DirectX: AMD Radeon R7 graphics (23.20.15017.3010)
If Lightroom is not using Direct2D, it is using OpenGL for the GPU acceleration and should still render your images and helps speed up the overall app performance as described here: Adobe Lightroom GPU Troubleshooting and FAQ