It's possible that something is loose or a joint is flexing more than normal. Here are a few things to check

Check the headset by aplying the front brake and rocking the bike forward and back. Watch or listen for any movement of the fork at the lower HS bearing.

Do a horizontal stress test by holding the bike up and leaning it away from you, while you press one foot into the base of the crank. Watch for hints of excess flex which might show up with rim movement at the brake shoes.

Check that not only are the rims true, but that the tire centerline is true also. If your tires have a raised center ridge it can feel squirrelly if the point of contact moves on and off the ridge.

Lower tire pressure to 95-100psi which will increase tracking forces slightly.

Check that the rear wheel is square and centered by placing a straight edge against across rim on a secant, and noting where it meets the seat tube. Do this at the same height from both sides, and at the top and bottom of the rim, (all four must meet the tube the same amount off center)