After 30 min of driving loud squeal from rear that only stops if I brake

What is your question?

After 30 minutes or so of driving. Two mechanic shops said brakes are fine and couldn't recreate the noise, told me nothing was wrong. It is extremely loud and severely hinders our ability to drive it if we have to go any distance.

What makes this problem better or worse?

30 minutes of driving

How long has your 2016 INFINITI QX80 had this problem?

Few weeks