Initially the downgrade to kernel 5.14.21-150400.24.69 appeared to resolve the issue, at least with regard to the "Init MAC failed" error. However, now I'm getting error reports from the kernel without even suspending. It may well be a hardware failure, given the age of the laptop and that I had to partially disassemble it to replace the battery last year. So maybe this should be closed. Thanks for looking into it.