If you don't set a txpower, the radio should default to the highest power it is capable of, and that's usually what you want.
This is definitely a 5 GHz problem. It should be running the -ct-smallbuffers ath10k. Not using the smallbuffers version will definitely cause crashing on a 128 MB RAM. You can also try the non-ct ath10k.
i had test with the default country drive, but the problem is the same with this message:
Fri Jun 10 18:37:21 2022 kern.warn kernel: [ 2036.154251] ath10k_pci 0000:00:00.0: Invalid VHT mcs 15 peer stats