I loved this show.

That said, I think there is a combination of factors here with Trey singing up an octave. I agree that it kinda disrupts the song (in this case an otherwise really intriguing "Theme from the Bottom"), but it seems to be something that combines two things. First, as you get older, your vocal range changes substantially. All professional singers are aware of this. The other thing is their switch to in-ear monitors. It's just different, and you hear yourself in a completely different way. If you are not used to it or had been doing it differently for the last 40 years, it can seriously throw you a self conscious loop. My hunch is that a combination of both of these things has gotten into his head and he didn't like his sound in the lower register.

Or I'm overthinking it

Still. Great show. Can't wait to see how "Life Saving Gun" grows over time.