this has been bugging me for weeks. quad flies totally fine in hover, punches out clean, but somewhere around 60-70% throttle in a sustained forward flight it starts this weird high frequency oscillation. almost looks like jello in the feed but its definitely not the camera, you can see it in the blackbox data too. filters are tuned the same as my other identical build and that one is fine.

ive already rebalanced all the props, checked motor screws, reflow soldered the ESC connections, and even swapped FC just to rule that out. RPM filtering is on. not sure what im missing at this point. the only thing different about this build is it took a pretty solid hit about a month ago but i couldnt find any obvious frame cracks.

have you checked the frame arms more carefully? like not just a visual inspection but actually flex testing them by hand? carbon can crack internally without it being visible on the surface, especially on the underside of an arm near the motor mount. i had something similar once and it turned out to be a hairline crack that was basically invisible until i put a light behind it. the arm was flexing just enough under load to cause resonance but only at certain airspeeds where the aerodynamic forces hit a sweet spot.

also worth checking if all four motor mounts are sitting completely flat. even a tiny amount of motor tilt from a bent mount can cause this kind of thing and its easy to miss.

could also be a prop shaft that got very slightly bent in the crash, like just enough that its out of balance at higher RPM but not enough to show up when youre spinning it slowly by hand. ive been fooled by that before. try swapping in a completely fresh set of props from a different batch and see if anything changes. also what motors are you running and do you have notch filters set for their KV range?