Teams custom app stops working after a couple of weeks and only works again after removing/adding

I've created my first Teams Adaptive Cards app hosted in Azure. I uploaded it as a custom app to Teams, and it works perfectly, but only for a while. The adaptive card is triggered by an external site making a fetch request to the endpoint /notification{id}.azurewebsites.net.

The issue I am facing is this:

The app works for a couple of weeks with no issues at all. Then it suddenly stops working. The weird thing is when I remove the custom app from Teams and then reupload the exact same zip file via the 'upload a customised app' option, it works again without any issues for another couple of weeks (roughly). To be clear, I'm uploading the same Zip file without repackaging or modifying the code or Azure settings.

When I check the console from the external site, I get the expected response back, and the app services logs data is precisely what I expect, i.e. no change from when it's working in Teams and not working in Teams. What could be causing the app to 'expire/stop working' after a few weeks that is rectified by simply removing the app from Teams and adding it back?