After 10 years the issue is still unsolved.
nov/13/2022 08:53:51 system,error,critical router was rebooted without proper shutdown
nov/13/2022 08:53:57 system,error,critical kernel failure in previous boot
nov/13/2022 08:53:57 system,error,critical out of memory condition was detected
Tried clean installation with netinstall, no better results.
> system resource print
uptime: 5h57m
version: 7.6 (stable)
build-time: Oct/17/2022 10:55:40
free-memory: 7.5MiB
total-memory: 32.0MiB
cpu: MIPS 24Kc V7.4
cpu-count: 1
cpu-frequency: 400MHz
cpu-load: 7%
free-hdd-space: 110.3MiB
total-hdd-space: 128.0MiB
write-sect-since-reboot: 293
write-sect-total: 1703186
bad-blocks: 0%
architecture-name: mipsbe
board-name: RB751U-2HnD
platform: MikroTik