There must be something wrong with LibreELEC here. I now got my older HTPC as my main player, since my NUC is going back to Intel for service.
A new LibreELEC installation on a USB-stick, and on reboot it takes a long time. Showing some kind of info about the shutdown process on the TV, like my first post attached picture. But, without the red text about errors. It might be that the red text just isn't available on the TV, but I don't know.