Screensaver issue ? OR user issue?

Hello everybody and happy new year !

I think i have found an issue on my
with the official n.20191127 or with the chimpthechimp’s unofficial p.20191114, some times, i don’t understand why, I am stuck on a black screen with a blue or a red zone with date and clock on the top.
I don’t know how to get out of this screen, and I have to reboot the system.
It is probably just a screensaver !
But how to escape ?

Thank’s for replies.

i have the same issue on my S5 SM-G900F (klte) to.
i am on dev 0.13-2020120889008.

I think it is because a bad management of the phone’s magnetic sensor for flip-flap cover