Quoted from flynnibus:
Not necessarily. No wear concerns for magnets that just look to move/influence the ball. It's the magnets that try to GRAB the ball that cause wear issues.
No one has mylar'd their twilight zone mini-playfields... for the same reason. It's not unexposed magnets that cause wear... it's magnets that need to grab and the edges of magnets that are wear concerns.
If they aren't looking to grab and hold the ball, rather just push/pull the ball in pulses - the magnets don't need to be as powerful or long pulses and don't drag the ball as much.
It looks like it's circling faster and tighter here, and the quality and durability of pfs Stern has recently been sourcing aren't really comparable to original TZs or recently remade mini pfs.
I'd say it's a concern.