Sounds like your piano had it's keys recovered and the person doing
the rebuilding got carried away with filing the sides of the keys.
Once you file away the key sides your stuck with what you have.

I've seen some technicians use molded keytops and fronts and not file
the sides.  This would look good but would feel horrible to play and be
very obvious to anyone trying to play the piano because the tops would
stick out over the sides.  You could try to space the keys a little
more uniformly by slightly bending the front key pins one way or the
other.  Be careful.  It doesn't take much.

Hollis Mull