TestFlight App No Longer Available for Installation

I uploaded my app to App Store Connect to test it through TestFlight.

Initially, I was able to download, install, and test the app without any issues. However, the following day, the app was no longer visible in TestFlight, and I could no longer download or install it.

It has now been three days, and the issue still persists. I have been unable to access or reinstall the app through TestFlight.

Could you please help me understand why this happened and how I can resolve the issue?

Thank you for your assistance.