What I'm saying is that I can't mechanically diagnose anything over the interwebs.
BUT...a strong braking pulse at lower speeds all the way til it stops is an isolated issue. It's not going to be dirty pistons, head bearings, loose fasteners, bent wheel, none of that. It has to do with the brakes. If it has ABS, that opens up about the only other thing it could be besides the rotor in my opinion. Rotor/caliper/pads are precision parts and any little offset can be felt.
Who knows, I know I'd probably go back to the shop and tell them they need to warranty that new rotor they just installed. But they count on people not being mechanically inclined so they say dumb stuff like "no man, it's supposed to do that....it's a petal rotor." and they get out of replacing it.