Photoshop v21 all versions crash at startup for me. If I restart my computer and launch PS, it will load properly, but if I close it and work with other CC apps, it will not open unless I restart and launch PS first.
PS 2020 works fine and I continue to use it as my preferred version.
iMac (Retina 5K, 27-inch, Late 2014
4 GHz Quad-Core Intel Core i7
32 GB 1600 MHz DDR3
AMD Radeon R9 M295X 4 GB
Here's the first part of the crash report and I can provide the full report if needed.