Tasmota not available for a few days

I have been running HomeAssistant on a Pi4 for about two weeks and have also successfully set up a Sonoff Tasmota read head for the electricity meter.
I then set up a reed contact for the gas meter.

After I then took care of a few dashboard items, Tasmota suddenly disappeared. Around this time, the TasmotaAdmin add-on was also updated (which I never actively used).

Could this be related to this?

According to the data, the device was not updated:
Program Version
Build Date & Time 2023-02-23T11:18:31

I have already recreated the “Tasmota” integration without success.

The symptoms:
The entities have the status “Not available”, accordingly no more data arrives.
In the Tasmota console I read “Connect failed to homeassistant:1883, rc -2. Retry in 120 sec”.

The Tasmota is visible in the MQTT Explorer, but the last “sensors” message is from 06.11.

When I remove the integration, it is recognized and added again a few minutes later → with the status “not available” :frowning:

What can I do to make the Tasmota correctly recognizable again?
It seems as if something is wrong with the Tasmota, the code “rc -2” probably stands for a problem in the connection. However, I can access it without any problems via the URL of the Tasmota…

Thanks in advance

(and sorry for my English, comes from a translator from German)