So df -h
indicates that you have enough free space.
To fix the issue we can remove problematic packages using low-level commands:
sudo dpkg --force-all --purge linux-headers-5.11.0-22
sudo dpkg --force-all --purge linux-headers-5.11.0-22-generic
sudo dpkg --force-all --purge linux-headers-generic
and then reinstall the headers package by
sudo apt-get install linux-headers-generic
and install upgrades then by
sudo apt-get install -f
sudo dpkg --configure -a
sudo apt-get dist-upgrade # to get new dependencies