Welcome to the forum
USB is working fine with all kernels alike here, so it might be related to your hardware.
A quick fix would be to simply exclude the kernel from being updated for now. Simply add “exclude=kernel*” to /etc/dnf/dnf.conf.
[main] gpgcheck=1 installonly_limit=3 ... exclude=kernel*
The vc4 driver introduced in the 5.10 kernel series does not fully support the rpi4 (yet). Video works fine, but the vc4_hdmi sound driver still seems to be broken on the rpi4.
You can simply blacklist the vc4 to get working sound via snd_bcm2835, but you will be set back to the (working) fb driver for video. Hwaccel for video is (not yet) implemented anyway
You can test it by simply adding module_blacklist=vc4 to the kernel cmdline.
To test this just for the current kernel, add the entry to the appropriate config file found in /boot/loader/entries/.
To make it permanemt for all add the parameter to /etc/default/grub.
GRUB_CMDLINE_LINUX="module_blacklist=vc4 ... rhgb quiet"
grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
Alternative you could add an blacklist enty to /etc/modules-load.d/ and regenerate the initrd.
Regarding the wifi issue I didn’t bother investigating yet, since I don’t use it