I have a jolla phone. In developer - mode, the jolla phone offers an IP
connection over the USB cable connected to the laptop. This worked flawlessly
until TW 20221206 or one iteration earlier in November without that I have ever
touched configuration or made any handcrafted one (since 2014 or so). 

Suddenly, connecting the phone did not produce an IP connection anymore. All
prerequisites are there. lsusb sees the phone. ifconfig shows the interface as
enp0s20f0u9. But no connection happens. 

I then created an entry manually in Networkmanager that is restricted to
enp0s20f0u9. In this connection, everything is set to automatic. Now plugging
in the phone works again. 

Somewhat, the default configuration was broken in one of the lastest updates on
networkmanager and IP over USB (not the other way around) connections do not
work out of the box anymore. Configuration manually fixes the issue.