Comment # 2 on bug 1190608 from Bunte Katze

As proposed by https://www.reddit.com/user/ditzypoet/ I tried booting kernel
5.14.2-1-default only with minimal boot params:

linuxefi /boot/vmlinuz-5.14.2-1-default root=/dev/mapper/system-root
${extra_cmdline} resume=/dev/system/swap mitigations=auto

However, the result was unfortunately *exactly the same* as with my default
boot params (which grew to a long list after applying a whole number of
workarounds to fix adjustable laptop screen backlight, keyboard backlights
etc.):

linuxefi /boot/vmlinux-<kernel version> root=/dev/mapper/system-root 
${extra_cmdline} resume=/dev/system/swap acpi_osi=! acpi_osi=Linux
acpi_os_name=Linux acpi_rev_override=1 nouveau.modeset=0 nouveau.runpm=0
pcie_aspm=force drm.vblankoffdelay=1 scsi_mod.use_blk_mq=1
mem_sleep_default=deep mitigations=auto