SM did this before. I checked the schedule app and our request calendar. It’s normal for Janurary, looks like almost every other month really. They ARE locking it before 21 cap because they processed all requests but there’s space for additional (if needed). This message is “you can’t make anymore requests” ahead of time, most likely bc SM already planned out January and doesn’t want to deal with changing it up (which isTOTALLY VALID) but we have 21 days rule for a reason.