My theory is the mini has really weak front arms that twist easily and can cause a prop strike
Just grab the motor and you can see it will twist without any effort, they put that stupid foam filler piece in order to save weight , but it does nothing structurally.
You'll notice the rear arms have plastic inserts to improve the stiffness.
With many flight cycles the plastic on the front arms will weaken further and your prop strikes could get worse.
Have you also checked the props for any deformity
Were you flying in high winds, have you crashed before ?
This is how some people have remedy the issue
This is to make the arms sturdier, thus less motor vibrations. I got this idea from Lindsay White but made my own model from scratch. Printed 0.4mm PETG 100% infill. Removed foam and super glued the part.
www.thingiverse.com