Steering Wander Mazda6 GT

2014 Mazda6 GT
I bought a used Mazda6 GT with 50k KMs on it 2 months ago. From the start the car had a slight steering wheel wandering problem on the highway.
On a flat straight highway the car feels as if it is too windy outside and pushing the car either slightly left or right. I constantly adjust steering wheel back and forth a tiny bit like a boat just to stay in my lane.
However, it is not windy what so ever. My first thought was tires. Recently I bought 4 new winter tires with 4 new steel rims. Got them balanced on a hunter road force machine and got the alignment done from Mazda dealership. To my surprise car still feels exactly the same!

I am now suspecting something on the suspension is either worn out or needs adjustment. Has anyone here experienced something similar or is there a common suspension part that needs to be replaced often? The problem is not bad enough to start spending money diagnosing it at dealerships. It is just annoying.

Can there be a positive or negative camber even after an alignment?
2014 Mazda3 S GT auto, 2008 MX5 6-speed
A good alignment shop's techs typically know suspension components and can spot worn-out parts or loose hardware. I recommend that you take your car to such a shop, especially if you do not know the maintenance/repair history of the car. Another possibility is a bad wheel bearing, although noise during cornering often reveals this type of issue.