Sounds like a problem with the brake rotors.
The brake rotor can be warped or have ‘hard spots’ on it which change the friction around its circumference.
If I noticed this vibration in my car, I would do the following to start:
- Verify that the lug nut torque is equal on all wheels by loosening and retightening each one.
- Uneven torque can warp the rotors
- Doing ONE lugnut at a time means you don’t even have to lift the vehicle off the ground.
- I do some hard stops from speed a few times to ‘let off the smoke’.
- Heating the pads/rotors can help lubricate them and reduce hard spots
Both of the above cost nothing to do and may solve your ‘vibration’ problem. If the problem persists, consider new pads/rotors.