ABS Problems: Causes and Solutions

Hello everyone.
I'm having a problem with my VW Passat 1.9 TDI. Both the drive shaft boots were torn, and I had them replaced. Since then, whenever I brake, I sometimes hear noises like I'm braking on snow. It doesn't happen often, but when I press the brake pedal while rolling, I sometimes hear a humming sound coming from the engine compartment. Can anyone help me with this?

Hmm, could the ABS rotor have been damaged during installation or removal?
That would be the initial assumption.

Or the ABS sensors were not pulled out far enough before removing the drive shafts and are now damaged.

Okay, try removing the sensor and see if any dirt has accumulated at the tip. If there is, remove it. To do this, rotate the wheel and examine the ABS ring in the hole (for a complete rotation). You should be able to find it then.

Good day everyone.
I would like to sincerely thank you for your numerous responses. As you have already mentioned, the sensor was slightly dirty.
and the problem is solved.