If you see above grey screen after starting Lightroom Classic, there might be some pointers what to do.
Try to re-install
The first attempt to solve the problem should be to re-install the software.
Have a look at the following log file
~/Library/Application Support/Adobe/Lightroom CC/lrcc_console.log
In my case the following error showed up:
ERROR: Failed to create directory (/Users/foobar/Library/Application Support/Adobe/CameraRaw/), errno 2, parent directory (/Users/foobar/Library/Application Support/Adobe/) has permissions 40755 *** GPU Error: Cannot get GPU Host App directory *** 2023-07-05 09:17:39.902 Adobe Lightroom[5676:61231] initializing Camera Raw: dng_error_unknown 0: global error - C 1: [unnamed] - 1250880549:121+7 2: [unnamed] - C 3: global pcall - C
Solution was to remove the Adobe folder in „~/Library/Application Support/“ and re-install. The problem was gone.