There’s an (unfortunately closed) issue about this.
I thought the warnings when kodi is off at HA start have been fixed, but i realised now that i disabled them in logger.
Looks the same like I have with Amazon stick. it also floods with ‘warning’ messages all time while the stick is offline. But Amazon has some meaningful msg to indicate this case instead of strange ‘Config entry for kodi not ready yet.’
In my setup Kodi is off. So, if I restart home assistant when kodi is off the home assistant gets this message until I start kodi.
Most of the integrations with Home Assistant for some reason, when they cannot communicate with the device set the device as unavailable. Before the integration the device was set as Off. This is happening for my standby Panasonic TV and now for my standby Kodi.
It just Kodi is giving this warning if it cannot communicate with it during the restart of Home Assistant.