@hesspoint hm… sounds like maybe a bad cable? or a bad port on the pi

@sdetweil Thanks for the suggestion. You were right. It was a Home Assistant automation going haywire. The automation switched off the screen via MMM-remote-control. On top of that somehow the “blank screen” option in the Pi settings was turned on again (no clue why, maybe after the last update). Anyhow I now tamed the automation and turned off the blank screen again and now it seems to be working normally again

@hesspoint Update: There is actually a custom HA integration that is awesome: https://github.com/sindrebroch/ha-magicmirror So I switched form the REST API to that integration and it is even better