I set up rtl_443 to push to Mosquitto, to which my HA is talking. This was about 2y ago. About a week ago, this went to Unavailable. I am not sure why, the rtl_433 process has an uptime of >40d.
With some digging in MQTT Explorer, I can see that the Topic has changed from /53/ to /29/. The entities for this device cannot be edited and I cannot recreate them. I have no idea how I did this originally. I don’t have any rtl_433 integration installed. I can’t see anything related in any .yaml files.
What I have done to get this working again is to create a new sensor in configuration.yaml pointing at the correct topic. If the topic ever changes again I will edit this sensor and move on with my life.