I'm running Ubuntu 20.04.1 (kernel v5.8.0-43) on my X1 carbon 2019 (gen 7). Everything works just fine: Sound, wifi, function keys, fingerprint, etc. However, once in a while, I guess after the machine gets unplugged then plugged, strange things happen: The function keys, except for volume control, no longer work. Closing lid does not put the laptop into suspend mode. Fonts break on some browser (Brave) but not the other (Chromium). If I reboot the machine, these problems won't happen.
My best guess: When I power source change, some services just stop working, causing these problems. But which services? I don't know. Sometimes it happens, sometimes it doesn't, so there has to be something more than just the power source change.