Sure thing.
Looking at the system.conf reminded me that there is also the watchdog timer that might be extra long … and for whatever reason manjaro leaves the watchdogs on and a minority of people disable them.
So in the off chance that is a source you can disable watchdogs … and/or … augment the system watchdog options… which manjaro ships in a funny state:
#RuntimeWatchdogSec=off
#RuntimeWatchdogPreSec=off
#RuntimeWatchdogPreGovernor=
#RebootWatchdogSec=10min
#KExecWatchdogSec=off
Which should probably really look like:
RuntimeWatchdogSec=off
RuntimeWatchdogPreSec=0
RuntimeWatchdogPreGovernor=
RebootWatchdogSec=off
KExecWatchdogSec=off
(for more general watchdog stuff: [HowTo] Disable watchdogs (and silence "watchdog did not stop!"))