The newer Carbons and the X1 Extreme have had a rougher time than most Lenovo laptops. My T480 and T580 were pretty much perfect from the jump, but my X1 Extreme remains disappointing.
I installed Ubuntu 19.04 on X1 Extreme Gen 2 and didn't have any issues. Upgrades to 19.10 and 20.04 have been painless as well. Everything basically works.
I have an X1 Extreme Gen 1 and it's had power/battery issues since I got it.
Yep same on the Gen 1, it's an awful machine.
Running 20.04 on X1E G2 without issues here.
Recently bought T490 worked with Debian stable out of the box.