Concrete block steps discolored - What to do?

That will always remain the same. We have a wall made of exposed concrete stones. They chalk and discolor.

The manufacturer, of course, protected themselves beforehand.

That is normal with concrete - sometimes it is even deliberately used as a stylistic device (it lets the concrete "live"). If you don't want that, you will have to paint or seal it. The question is how sensible that is in the garden. I would accept the aging of the concrete as a process. And if you absolutely don't like it, you can possibly lay tiles over it, which will remain as they are.