Xfinity App not working on Firestick

I have a couple of TVs with Amazon Firesticks for streaming. As of October 2025 (probably after software updates), the Xfinity Stream app does not work anymore.

For live channels, the app keeps buffering and does not show any content.

For recordings, it does not play any of them.

Before these updates, it worked fine with all the features.

Current version for the FIRE OS is 6.7.1.1 (NS6611/5866).

Current version of Xfinity Stream: 8.12.0.2517.

I also tried this app in a Roku Premiere 4K, and it does not work either. It presents the same issues.

Any help fixing this problem would be appreciated.