so this has been driving me crazy for probably two weeks now. quad just cuts out when i punch it hard, like full throttle for more than maybe half a second and it just drops. motors spin back up after a second or so but obviously thats not great when youre 40 feet up.

its a 4inch running 4S, nothing exotic, relatively new build. i looked in betaflight and there are some spikes on the motors tab but i genuinely dont know what im reading. someone mentioned desync but i thought that was more of an older thing? also possible i have a bad solder joint somewhere but i already reflowed everything i could see. flight controller is a SpeedyBee F405 if that matters

gonna try swapping props tonight because one of them did take a hit last week but im not super confident thats it

desync is still a thing, usually shows up as exactly what you're describing. check your ESC firmware first ? if youre on an older BLheli_32 or even S version try flashing to the latest and see if it helps. also look at your motor timing in the ESC configurator, high timing can make it worse under load.

the other thing id check is your battery. if its a older pack or a cheaper one it might be sagging hard under punch and the FC is brownout protecting. stick a capacitor on the battery lead if you havent already, 1000uf 35v or higher, helps smooth out the spikes. might not fix it completely but its worth ruling out

had the same symptom last year and for me it turned out to be one motor with a slightly bent shaft. not enough to see visually but it was vibrating bad enough to trigger something. swapped the motor and it was fine immediately. might be worth throwing a motor on the bench and spinning it up slow while you look at it from the side