I noticed that our app stopped working on a test device under Android 6. After researching, I found that this is due to the fact that the certificate has expired.
more here Flutter on Android 7 CERTIFICATE_VERIFY_FAILED with LetsEncrypt SSL cert after Sept 30, 2021
At the same time, according to the analytics, devices with 5 and 6 Androids continue to work. Why is this happening? As far as I understand, the certificate was supposed to expire on October 1, 2021, and all devices with old OSes should have lost the ability to work with our backend.
PS even more diligent is that exactly the same devices with the same OS version as my test device are working