So, then I reverted to my working 5.14.10 kernel and did a:

dnf update --exclude=kernel*

which included an update up to:

uboot-images-armv8-2021.10-2.fc35.noarch

and re-booted. Everything is fine.

So, the only known problem I have is the 5.15.13-200.fc35.aarch64 upgrade.