I use only about 300 bytes (manually counted ...) for my variables and amongst them about 36 are stored in bank 0. None of the additional variables used for the new capabilities is stored in bank 0.
Remember that PBP itself uses a bunch of variables and it most likely needs to use BANK0 for them for the same reason that you want to use BANK0. The number of variables PBP uses depends on what library routines it includes and, of course, if LONGs are enabled or not.

So, when you added new capabilities to your code PBP included some library routine that uses a system variable that wasn't needed before. It was put in BANK0 pushing your variable(s) out.

That's my guess at least.