Car drives great. But when i drive 60-70mph down the hill and try to brake a little, steering wheel shakes side to side. But if i brake harder and hold steering it is not so noticeable. If i brake on the straight road no shaking,but a bit of squiling noise from pads. Any ideas? Rotors have been replaced 18k miles ago.

Should i replace rotors and pads? or it is something else?

i took car to local LesSchwab they said it looks like rotors are warped,but they not 100% sure,as they said could be something else.