I have had the same problem for several years.Earlier with Manjaro I managed it with the above mentioned trick. Meanwhile it is no longer existent with Manjaro, I don’t know, probably better hardware detection. Here with EndeavourOS I got again these error messages from Watchdog at shutdown. I have again blacklisted the same things in /etc/modprobe.d/blacklist.conf. It works, but now I’m not sure if what I put in blacklist.conf is really correct.
lsmod | grep -e dog -e wdt -e tco gives me NO output, so I can’t determine what needs to be blacklisted. Processor is i5 2500K.
Again, my blacklist.conf currently has the following content:
# disable intel mei (including mei_watchdog)
blacklist intel_pmc_bxt 16384 1 iTCO_wdt
blacklist iTCO_vendor_support 16384 1 iTCO_wdt
# Do not load the 'iTCO_wdt' watchdog module on boot.
blacklist iTCO_wdt