ABS system pulses when slowing to a stop?

Hello,

Is the ABS light illuminated on the dash?
Typically, where there is an issue with the ABS system the light gets triggered.
Retrieving the ABS code(s) could help with the diagnostics.

Here is a helpful video:

https://youtu.be/rTtAnsOlZU4

It is possible to bump an ABS sensor while installing the brakes. You could have a sensor that got loose or disconnected.

Keep in mind that wrapped rotors can also create pulsing on the brake pedal. If the brake rotors were not changed, this could be another possibility.

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd

Checking the brake rotor lateral runout can help determine if the rotors are wrapped.

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.