Spiral of doom is part of the fun.
What’s not fun on Zwift is how in ERG mode the effort seems to increase on downhill sections and is easier on uphill sections. So I try to find the flattest routes to get rid of that effect and keep the effort level for all of the interval blocks.
I’ve had that for a long time and don’t bother reporting it because there is no way to prove it without buying power meter pedals and everyone says almost the same thing from script so no point in going further.