You are likely hitting this specific change for your router made after 21.02 but before 22.03, and getting the related warning...
- https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=8a042450d8fd4e2916fb0e87d65bbbd7e3a97130
apm821xx: MX60(W): re-enable + allow bigger future kernels
See advice in the commit (and you might document that to the device wiki).