Not saying you for sure have pests. Just when other likely causes of reduced polyp extension have been examined, it's worth discussing.
Early in the aefw infection process not all acros are infected. I had a 12"+ pink millepora which used to be super pink and very furry and then displayed reduced polyp extension and became pale. It was being consumed by aefw.
Try blowing current on it with a turkey baster or handheld power head and see if aefw fly off.
Flatworm Exit is effective against planaria, but not against aefw.
Redbugs and red planaria are not the same. Red planaria look similar to flatworms, in terms of being flat and squishy. Redbugs are little arthropods, sort of coral fleas or ticks. They come in colors besides red though red head with a yellow body are the ones I've seen most. They're very small and hard to see. I usually notice them when I'm doing macro closeups of a coral. Then they're more obvious. Redbugs also move quickly more than flatworms.
I hope you don't have any pests and your milli soon returns to the fur beast it should be.