I do not know the reason for this problem.

But, after updating (yesterday) linux-5.9.9-sparky-amd64, iptables 1.8.6, and all other available updates.
And, after rebooting the laptop, UFW failed (and does not start) with the 5.9.9-sparky kernel.
However with the official debian kernel (linux 5.9.0-2-amd64). There is NO problem, UFW and iptables work correctly.

It has also been tested with an alternative kernel (linux-5.9.9-xanmod1 stable), and no errors have occurred. UFW starts automatically and without any problem.
(By the way this kernel, I had to install it manually, through the terminal; because
using APTus nothing is installed).

Cheers!!
