Though a new firmware was release for ThinkPad X1 Carbon G6 since last month, 2020/01/23, I only found about this today.
Unlike the firmware for Dell’s laptop, once can easily update it with
fwupmgr if your Linux system supports it.
Here’s what’s changed in this release.
CHANGES IN THIS RELEASE Version 1.45 <1.45> UEFI: 1.45 / ECP: 1.20 - (Fix) Fixed an issue where a system hardware controller device might disappear at 2nd boot.
To update it on Fedora 31, run:
# fwupmgr update