Custom teams app not found in store and not responding via Teams Channel

Question

I have an office365 tenant with my own teams environment. Since the beginning of this year, I have had no issues with uploading a bot and developing it (via tunneling to my local system).

However, since a week, the Teams channel is not working. I do not get any messages sent to my bot. No changes have been made in this last week to the code nor to the setup.

The same bot via tunneling works on Web Chat (in Azure while testing the bot). So the bot code and tunneling are working fine.

However, I am not able to find any logs corresponding to the Channel to bot communication in Application Insights.

Creating a new bot and uploading it causes the same issue. Any messages sent from Teams does not seem to work.

Selecting a button on an existing adaptive card (from when the bot was working) shows the error saying the bot has been disabled (but it wasn't disabled/blocked, currently shows active and never was disabled/blocked)