To downgrade, use: sudo apt install libkf5networkmanagerqt6=5.18.0-0ubuntu1
and then restart. Logging out and in might work as well, I haven't tried it. I just rebooted.
To downgrade, use: sudo apt install libkf5networkma nagerqt6= 5.18.0- 0ubuntu1
and then restart. Logging out and in might work as well, I haven't tried it. I just rebooted.