Entire layer associated with supports is underextruded  

Entire layer associated with supports is underextruded

I am having a layer issue after updating to 5.1. The entire layer at the top of support layers seems to be underextruded. I am using 0.25mm Draft, generic PLA and PETG settings, and default MINI settings plus a PID tune (M301 P14.5 I1.0 D52.0 ; Set Hotend PID - BROZZL Prusa Mini Heatbreak - Titanium Alloy, Tungsten Carbide RepRap M6 Nozzle, levendig|dsgn Silicone Sock-X). I'd appreciate any suggestions.

Here's an example with PLA. This is a single layer that sits on the supports.

And this PETG print has several layers that are supported on the dragon's claws.

https://www.printables.com/model/557569-low-poly-dragon-dice-tower

I've tried adjusting a bunch of settings:

1. External perimeters first
2. much slower print speeds (from 55mm/s perimeters to 40mm/s, 40mm/s ext perimeters to 30mm/s)
3. 3 perimeters instead of 2
4. more fan on the PETG print