no IPV6 via Mobile Hotspot

I have two Android phones. Same hardware model, one with android 10 and the other with 11. Both phones connect to the same telco. On both phones I can browse to test-ipv6.com and get a 10/10 indicating IPV6 on each handset is working. I then enable mobile hotspot and test from my laptop. Via the android 10 phone the laptop receives a V6 IP and the above website reports a 10/10 from the laptop Via the android 11 phone, the laptop does not get a V6 IP, and the above website report 0/10. I have looked though as many settings on Android 11 handset as I can, and scoured the internet for ideas but I cannot determine why a V6 IP is not allocated from the 11 handset. Ideas?