Aligner buttons (attachments) are made of a light-cured material and bonded to the enamel of the teeth. White fillings, build-ups and bonding are made of the same kind of material. Staining isn't expected if the button sits tightly against the tooth and its edges are well adapted and polished. If it does happen, though, the solution is to polish the edges of the attachment or, if it's defective, to replace it.
This answer is for general information. Your own case needs an examination by an orthodontist.