It seems that the sampling rates/algorithm used to create the power duration curve at the end of the workout is buggy - looking at the picture below, it shows my power increasing at some points, which doesn’t actually make sense for a power duration curve.

I just completed a zwift ride where I was following a workout my coach gave me, but was on the “just ride” mode on zwift. The workout had two main sets of intervals - 10 x 30 seconds hard, 15 seconds easy (I can share the specifics if that would help). I suspect that the power sampling rates for different durations lined up oddly with with the time intervals - if you look closely, there are 2 sets of 10 “peaks” grouped together as bumps here on the power duration curve, corresponding perfectly to the intervals I did.

Not sure if this is worth spending the time for zwift engineers to fix, as it’s probably non-trivial, but at the very least it’s very interesting and definitely not the intended behavior.