If he's competing bonuses that are still a 'work in progress' that certainly explains the dropping scores. Personally, I feel the judges at L6 become more 'punishing' of form mistakes than in L5.
A little tangential to your original question, but it's just got me thinking....
I find it interesting that in women's gymnastics, there seems a universal approach to "master each skill with perfect form as you learn it", whereas in MAG, there seem to be two distinct "camps" of thought..
1) Train clean basics only and don't even train bonuses/new skills until you've achieved and maintained that clean base. Don't compete a level unless you mastered (60's+) the previous one. There is no rush, so being 'in age' at level 8 is not as important as having as clean a foundation as possible. (Most won't start L4 until age 7/8, and repeating early compulsories common, but scores are high and teams win a lot. Not many will be 'in age' for nationals at L8).
2) Most boys are sloppier in general when they're younger (under 10-11 ish), so teach them more skills now with 'good enough' form (not completely wrong form), and they will clean up over time and ultimately be better prepared for optionals. Don't stress over the flexed feet now. "Getting through" compulsories is the goal (I have literally heard more than one coach at different gyms use those words). Only scores in optionals really matter, and if you don't teach the mechanics of harder skills early (younger), it will be harder to catch up and be competitive in optionals.
Personally, I prefer a middle ground, but I can definitely point out programs that lean one way vs the other by watching their gymnasts, both in competition, and their level/scoring histories.
I will also add that for my particular son, Camp #2 was primarily what he needed for levels 4-5, and into learning skills for 6, but now, for L6 season, is at a point where clean-up is, I think, what is serving him best. I can imagine, though, that for L7, he might again need a period of focus on skill-acquisition and sacrifice the performance-form somewhat to keep on track for L8. Will mean fewer medals in the short term. I'm ok with that.