If I read this right, they’re increasing the maximum non-prescription dose of vitamin D from 1000 IU/day to 2500 IU/day. This seems to be the official dose on the label; nothing prevents you from taking extra pills. There’s some discussion of methodology; the new limit seems to be a maximum known-safe dosage for someone in the 95th percentile of vitamin D intake. There’s a fairly large safety margin built into these numbers for risk tolerance.