Redmi AX6000 lost 5 GHz radio

Installing and Using OpenWrt Network and Wireless Configuration
2

This seems very similar to this older thread: 5 GHz WLAN craps out (upon radar detection?) - start_dfs_cac() failed - #9 by Borromini

I too am using 160 MHz width.

config wifi-device 'radio1'
  option type 'mac80211'
  option path 'platform/soc/18000000.wmac+1'
  option band '5g'
  option country 'US'
  option cell_density '2'
  option txpower '24'
  option beacon_int '100'
  option htmode 'HE160'
  option channel '100'

I added this line to /etc/config/wireless and will see if it helps to recover:

option channels '104, 108, 112, 116, 120, 124, 128'