Water and RH may be entering the masonry system.
The brick veneer faces are covered with effervescence. Mineral salts.
In my opinion the brick top course was not sealed with a concrete cap, or the capping is EFIS and failed.
Gravity will carry the RH throughout that rectangular sand or concrete brick element.
The staining is from trapped moisture inside the masonry.
It is hard to tell if that cap is concrete or part of the EFIS system.
1.) If the is concrete with no capillary break it will effect the brick.
2.) Those are ***raker style *** pointing or masonry tuck.
It is banned in Quebec sense 1982.
It exposes the bricks( lead face ) edge.
Most masonry or concrete brick’s lead face, the 1/16 of an inch that is used for the esthetic is the water shield.
A brick face to exposed will absorb water.
That is why there are so many styles of pointing or tuck.
I would recommend having that pillar repointed
I would recommend a capillary break cut in the concrete if it is concrete.
If not, a flashing at the last course bedding can be cut in. Like step flashing on a masonry chimney.
You can have the staining removed by a professional.