I have also updated my omnia and mox classic to 6.5.0 and updated firmware and factory-image. On both devices the updates went fine. Thank you @mionica for extensive exploration and recommendations.
The mox is now having uboot version: U-Boot 2022.07 (Aug 15 2022 - 12:25:08 +0000)
And the omnia: U-Boot 2022.10-rc4-OpenWrt-r16653+119-44ce70f0e2 (Sep 15 2022 - 18:21:35 +0000)
However on the omnia, the fw_printenv command is still giving a warning message:
$ fw_printenv
Warning: Bad CRC, using default environment
bootcmd=bootp; setenv bootargs root=/dev/nfs nfsroot=${serverip}:${rootpath} ip=${ipaddr}:${serverip}:${gatewayip}:${netmask}:${hostname}::off; bootm
bootdelay=5
baudrate=115200
I updated the content of /etc/fw_env.config to text below, which matches the logic used in /usr/bin/fw_env-config-init.sh. However after rebooting my omnia, the “Warning: Bad CRC, using default environment” is still there.
/dev/mtd2 0x0 0x10000 0x10000
There was already extensive discussion about this, there is even post by @backon suggesting to fix it with:
fw_setenv bootcmd "env default -a; saveenv; reset"
Is this something, the turris team can recommend?