Hi Andre Konijnendijk ,
Apologies for the delay in response. How long does the Web app in the production slot unresponsive for? When you looked at the deployment logs did you see any errors or warnings that could be causing the issue? because it seems like there might be an issue with the deployment process.
You can try swapping the slots manually instead of using the automated process to see if that resolves the issue. If the problem persists, you can try redeploying the application to the staging slot and then swapping it with the production slot to see if that fixes the issue.
Please let us know if the issue persists.