It was similar in my case with my encoders with pull up resistors. Without connecting VCC they reacted somehow, but had some weird stepping behavior and did mix up decrement, increment and push somehow.
It is likely that if you look at the down side of the encoder pcb you’ll find some resistors in between the pcb lanes, which would probably measure something like 10 kOhm.
Alternatively you could desolder the pcb. For myself I opted against that kind of solution.