I think you need to keep the overall workout goal in mind. Over-Unders are about getting above and only slightly below Threshold work.
Assuming you have a reasonably accurate FTP, dropping intensity can lead to a real shift in effective loading on our systems and a step away from the intended adaptations.
That’s because we are usually talking about 105% to 95%. Lower that more than a few percent and you aren’t doing O-U any more.
I feel the best change in this case is to simply shorten the intervals. You still push the power into the prescribed zones, but limit the duration to something more manageable.
Completing as much and as many of those full intensity intervals is likely to be more productive vs changing the effective zones via dropping the intensity.