I agree with this point - there are two problems being caused by this
The first is common and not worth stressing about - when you drop your cadence post interval the power will drop below the new lower target. This is fine and not a big deal
The second is semi-unique to your setup which is that something related to your cadence post interval is broken. The cadence (and thus power) being transmitted by your DFPM is very very messed up and that’s causing TR to chase all over the place. You can mitigate this by following the advice elsewhere in the thread of not dropping cadence and being consistent all the way through but really you need to find and address the cadence issue with your power meter