Road bikes too. I wrecked my iPhone 8’s autofocus after riding ~1000 miles with it on a handlebar mount. Obviously there’s no engine vibration but chip-and-seal roads have a similar effect.
Though I do use a rubbery holder with good damping properties [1] and only recently moved over to a fixed one out of aluminum [2] for one of the phones, which could start causing this issue.
But I also had a quiet stock exhaust?
Probably the vibration in that situation didn't match the resonant modes of the camera components. It's probably a fairly rare event where everything lines up just right.