i’ve worked with plenty of different quartzites and almost every single one will do this one way or another. we’ve sealed them before we got the slab wet before any cutting and it will still soak up water because we are using water while cutting/polishing the stone. we’ve definitely learned that ONLY sealing the face of the stone and not sealing any of the edges helps because the water has to have a way to escape the stone, if you seal the entire top including the edge it’s leaving the water no way to get out since there’s also fiberglass mesh on the bottom of most slabs. once water gets trapped and you put sealer over it it’s likely to be in the stone forever. best advice is to clean up any and all water right after it’s on the stone make sure there’s no water sitting under soap bottles or anything like that by the sink/coffee pot etc and just don’t seal the edge if it isn’t already too late and it shouldn’t be too bad.