Encoder Readings Jump Randomly When Motor Speed Increases

Hi everyone,
I’m working on a motion control prototype using an STM32 to read a quadrature encoder. At low RPM the position count is accurate, but once the motor speed increases, the count occasionally jumps forward or backward by a few steps.

I’m using timer encoder mode, and the encoder cable runs close to the motor phase wires.

Questions:

Is this usually caused by electrical noise or timer input filtering limits?

Should I add hardware line receivers or RC filtering on A/B signals?

On the PCB, is it better to route encoder inputs with ground reference traces and keep them away from power sections?