Remove the dash from settings > dashboards and add a new one again.
Although you state to not have edited it, ‘strategy’ does not pop-up by itself…maybe unintentionally?
Even restoring backups from 3 months ago did not help. But your link (sorry, should have searched on my own) pointed to the bug where it was written about entities from Hue with same name.
And yes; I recently added a new room and named the lamp in this room just as the room.
So I went to the setting of the Hue app in HomeAssistant, opened the entities and sorted them by name. By reading I found the two entities with the same name.
Renamed one “Room Lamp” instead of “Room” (in the Hue app on my mobile device) and HomeAss is working fine again.
Additionally I had another duplicate which did not cause such trouble. The first one has an umlaut (“ü”) in it, the second does not. I assume this might be the issue.
Which brings me to the question why the bug has been marked as resolved
/KNEBB