3rd gen Tacoma OR feeling the rear bumps much?

I have a 2019 8k miles OR, i notice when driving on the freeway at speeds around 70mph ish the rear suspension feels like its oscillating up and down a bit "also hear the sound" . not sure if its just the sh*t freeway roads here in cali but i can feel it. i have the PRO suspension, and i adjusted my tire pressure back to 30psi after the dealer aligned my truck. I can only think that maybe it might be the rear tires needing balancing, or the tires are not the greatest "stock" and picking up all the imperfections in the road? I re-torque my U-bolt nuts, checked the rear shocks, and rotated the rear tires to make sure the mechanic didnt mount them incorrectly

so is this normal for the rear end on an OR? I dont have it loaded with any weight.

Not sure if it helps but my 3rd gen 4runner ran the same freeway kinda smoothly, but its heavy and i run Icons all around.

 

IIRC w.o weight in the back, the rear is a bit bouncy.

Check your tire pressure, that you aren't over inflated.

Throw two bags of cement by the tailgate

 

My sr5 access cab is the same...changed the oem firestones to 265/70 16 goodyears and lowered the tire pressure which helped. Seems the biggest help was a few hundred lbs in the bed when i have it. The ride on this truck is definitely not like my 2001 tundra.