ive been chasing this issue for like three weeks now and im about ready to just throw this quad in a lake. every single flight, motor 3 (rear right on my build) comes back noticeably hotter than the other three. we're talking too hot to hold your finger on it for more than a second, while the others are just warm. it's not throwing any errors in betaflight, no desync, motors all respond the same in the motor test tab. ESC telemetry shows the temps are elevated on that corner too so its not just me imagining it.

ive already swapped the motor out for a spare of the same model (Xing2 2207) and the problem followed to the new motor. so now i'm thinking its something ESC side or maybe a prop balance issue? the prop on that corner looks fine visually but i havent actually balanced them properly in a while. running 35x4 ESC. dont really know where to go from here

if swapping the motor didnt fix it and its still the same corner, that really does point to the ESC or something in the signal chain for that motor. could be a slightly damaged FET on that channel that's not failing completely but causing extra heat. also worth checking your pid tune - if that motor is working harder than the others to correct something (like a bent frame or off-center weight distribution) it'll run hotter even if the ESC and motor are both healthy. pull some blackbox logs and look at the motor output values in steady hover, if motor 3 is consistently higher than the rest you've got a balance/alignment issue rather than a component issue

yeah check the blackbox thing the other guy said, that's actually a really good point. i had something similar a while back and it turned out one of my standoffs was slightly longer than the others so the frame was twisted like half a mm and one motor was just constantly fighting it. seemed stupid but there it was. also double check your prop is actually fully seated on the shaft and the grub screw is tight, a prop thats even slightly loose will cause that motor to work harder and heat up faster than you'd expect