I think that rather anonymous device would be the Librem 11’s keyboard. Did you have the keyboard connected at the time??
You’ll notice that bus 1 device 30 gets recognised but does not show up in the output from lsusb and that the Librem 11 checks it to see whether it is an MTP device (such as would be useful if you plug in a mainstream phone or maybe a digital camera).
It looks as if some support for the Librem 5 is missing from the Librem 11 - which is not an ideal situation for Purism.
That said, many people would tether via WiFi, not via USB. Have you tried that tethering approach on the Librem 11?