Yes, iOS is up to date 12.4. I tried with all other data paths- WiFi, t-mobile data (eSIM), Verizon data (SIM).
All 3 doesn't work for my Verizon app, ever other app is working. My Verizon website works fine as well, I tried logging on all 2 data paths.
i also tried my Verizon app in iPhone 8 and iPhone X. I am facing problem only with XR.