I have tuned thousands of Gen 6 camaros and have only come across this maybe 3 times and it seems to be more prevalent or larger dip when adding E-85 to the mix.
I have seen it on 2 2017 Models 1 auto and 1 manual.
This one is a 2016 Camaro LT-1 M6 Cold air kit LT headers Flex fuel sensor
It is obviously some sort of Torque reduction request but from What?
gen 5 timing dip.jpg