I had a new system, and have installed OpenSUSE 15.5 on it.
So far so good, but later I noticed that using my mobile phone as network device was no longer working.

I found this page Tethering via USB doesn’t works

The solution proposed is working very well for me.

Open a terminal session, and become root.
Launch the following command to enable it:

modprobe rndis_host

Then it starts to work fine:

7: usb0: mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
link/ether ca:21:72:bc:83:00 brd ff:ff:ff:ff:ff:ff
altname enp0s20f0u4
inet 192.168.193.244/24 brd 192.168.193.255 scope global dynamic noprefixroute usb0

To make it permanent, create a blacklist file.

vi /etc/modprobe.d/50-blacklist-rndis.conf

With the following conent:

blacklist rndis_host

A bit later I found out that this change is done by purpose by SUSE. See https://www.suse.com/support/kb/doc/?id=000021587

Thus, in fact you have to adapt the file

/lib/modprobe.d/50-blacklist-rndis.conf

In order to avoid, to perform it as mentioned earlier.