I have same issue with Orange Pi Zero (Linux orangepizero 4.19.62-sunxi #5.92 SMP Wed Jul 31 22:07:23 CEST 2019 armv7l GNU/Linux)
I have running 20 devices. And now 4 devices have 1978 year and I can't connect thru ssh..
Devices sends every 30 seconds 'alive' message via MQTT, so I see this trouble but can't do anything because devices are remote and no access thru ssh.
I changed CPU speed to fixed 816 Mhz at available devices, and I will monitoring this situation and hope this help.
Maybe someone have any news/solutions for this trouble?
Founded how to remotely reboot OPi with 1978 date error using SSH:
ssh username@yourIP -p yourPort "echo 1 > /proc/sys/kern/sysrq;echo b > /proc/sysrq-trigger"