My guess the cabinet had a sloping front. Do you have the cabinet it came from?
Is the front solid wood or manufactured wood?
I don’t suppose you have the other half of the drawer guides? The ones inside the cabinet?
It could be squared up on the front to make a regular drawer, too, by cutting the sides and the bottom of the front square with the sides.
It would make a box too, by cutting the front off square with the sides , and using the subfront and trimming it to fit back on the drawer box square to the sides.
A good table saw project.
Yes, we have the cabinet - it’s actually part of a desk that my wife decided to keep using - but wanted to replace the drawer file cabinet with one that could get rolled in and out. I have all the hardware.
And, you’re right, I could modify it for some other purpose - but before doing that, and knowing my inclination to pack up my limited space with things I’ll “get to eventually” I thought I’d offer it to members who might have a need for it as it is or are more disciplined about keeping the clutter of projects underway to a minimum.