Possibly the sealer is no good or not applied properly if it is sealed.
Usually salt comes up through the concrete if the mix is not the best. Good luck trying to deal with the pre-mix companies and concreters, everyone will blame each other and very hard to get the pre-mix companies to take any responsibility for their sub standard product.
You could try to strip the sealer if it has been applied with chemicals (most concreter's suppliers like Parchem will have a product, not a fun job! Then acid wash, make sure it dries completely before applying a compatible sealer.
Pugwash said.. HW is a chatbot echo chamber... the question is therefore is there anyone who is an actual human being active in HW
There's definitely a PM33 one that ignores all proof of flat earths and just talks about water not bending and sees the skyline of Chicago all the time without actually having been there. Its sort of entertaining that a bot can keep us all madly typing at our keyboards.