So as you can see my slave cylinder for my drum brake on the driver's side failed. I replaced it and it failed in the exact same way. I'm thinking now something is up, I'm not exactly sure what though. I posted pictures of the new and old one. Any help is greatly appreciated!

 

I would definitely look at the brake shoe to the right of the cylinder to make sure it not jamming. The pistons push equally on both side so if one side jams its pushing the other side out. Also check the drum ID and make sure it's in spec, if it's too large it will push the shoes open so much the pistons will come out.

 

What do you mean by drum ID? I assume that's a typo?

 

Drum inside diameter.. should have a spec on the drum itself somewhere.. hopefully.. kinda like how a disc has a minimum thickness but opposite.
When you first got it apart, did you notice one side (one shoe) worn out more than the other?

 

Thanks a lot for explaining that! Yeah the DI and the shoe were worn down too much. Finally have working brakes again! 🥳