So, even with the PBR "reinforced" slot machine target, it still got bent back over only a few hundred games, and it still had enough spring in it to act as a catapult and fling balls behind the magnaflip sign and over the flippers.
Time to get serious. Yes, that's a bar of quarter inch steel backing it. Bracket is 25% wider and 50% thicker than the commercial "reinforced" one. Screws upsized as well for durability.
Now THIS solves the problem, ball now bounces off that target like any other target, instead of it being a near guaranteed airball.