We had simillar problem on CCR1009-8G-1S-1S+ with RouterOS 7.8 (we upgraded from 6.X to 7.X last week).
When one of clients become unstable and generated many reconnects, we experienced “rebooted without proper shutdown, probably kernel failure” errors and reboots.
For some reason it helped to switch OVPN to UDP transport and it’s OK since then. Anyone with same experience?
We did the change to an UDP before we read this thread and this similar one. So not sure if 7.7 is a solution as many comments says - since situation is stable on UDP, we stick with 7.8 for now.