Remove target from under playfield, if switch stack is screwed into the bracket, remove switch stack, 2 pairs of pliers to bent slightly. If switch stack is riveted same thing but be careful with the switch stack.
It will probably bend back over time, if there's space you can use reinforced standups instead - pinball resource sells one with a rib on it as do possibly other vendors like marcospec. It's a Capcom pinball design.
The disadvantage to beefed up targets is that instead of the bracket bending, it starts to rip out of the playfield. If you find old discussions of twilight zone's slot machine target you can see all the discussions of solutions over the years for this type of issue.
If the original stern brackets have a stiffening rib in them and it's stretched/separated probably best to replace the bracket vs. bending, based on the subsequent post about the swinks bracket.