I tried this, but still no wifi. My wifi works fine in 5.13, but not at all in 5.15. (However bluetooth works in 5.15 but not 5.13).
So…
I reinstalled 5.15.19-1-MANJARO (no wifi) and found the following in the boot log (journalctl -b 0):
kernel: iwlwifi 0000:aa:00.0: Loaded firmware version: 66.f1c864e0.0 ty-a0-gf-a0-66.ucode
…
kernel: iwlwifi 0000:aa:00.0: Failed to start RT ucode: -110
I moved iwlwifi-ty-a0-gf-a0-66.ucode to iwlwifi-ty-a0-gf-a0-66.ucode.bak and rebooted. The system came up with wifi working. Looking into the current boot log:
kernel: iwlwifi 0000:aa:00.0: loaded firmware version 63.c04f3485.0 ty-a0-gf-a0-63.ucode op_mode iwlmvm
Bluetooth is also working.