I'm not saying this is normal, but it's not unusual.
You could try swapping the Scart connections to the tv. Normally AV1 would take priority.
What happens is that peripheral devices eg freview, dvd, digibox etc send a signal through the scart connection to switch the tv to AV1, AV2, S-VHS etc.
When the current device switches off the tv goes back to normal input rather than the previous device.
Switching off and on again re-generates the signal.