All information edited into one question for your convenience.
There is no silver bullet to debug these kinds of issues, so the best we can do is to point you to the kernel debugging page for suspension and hibernation:
https://www.kernel.org/doc/html/latest/power/basic-pm-debugging.html
If you would run into issues over there, please feel free to post additional specific questions in this thread: no need to open a new one.
