Sometimes screen goes black

Hello

I use this setting:

/e/OS Samsung Galaxy S7 Edge refurbished
Device model SM-G935F
Android 11 March 22,2024
/e/OS 1.21-r-20240322388914-stable-hero2lte

Starting a few months ago I recognized that the screen sometimes goes into black and the only thing that can be seen is the current time. This is annoying because I am no longer able to unlock the phone for further usage. In case of a black screen I need to use the ‘Emergency Reboot’ buttons. I am pretty sure that it is not related to /e/OS 1.21 but happened also with /e/OS 1.20.

Any idea why this pops up and how to circumvent?

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