Tip stall does not necessarily mean there is anything out of kilter
If themodel is slowed to minimums -then yawed or simply eing held in a slight crab - the one panel is flying faster than the other - at least IT thinks it is .
so one panel drops first
You can check this out very easily and safely doing straight ahead stalls then bumping in rudder
On pattern planes in the past, it was almost always the case that a new model would "break" right -or sometimes "left " going into a spin.
In practice it was easy to decide which then, holding slight opposite rudder the break would occur straight ahead -or the thing would mush along. depends on the setup
anyway light plane heavy plane - all the same - even a perfectly straight model will break one way if there is some bias to EXACT straight ahead flight.