Because of the dry climate where we are, I usually don’t make an issue out of this type of plumbing vent run for bathroom fans.
I thought I’d post this recent inspection shot that I did, to see what others think about this?
I believe the perfect solution should be a vent, directly to the exterior.
(And in the imperfect world we live in, it sure looks like this would solve any possible moisture problems,
at least here in low-humidity-colorado.)