They are reallocating available aircraft to different flights, and in the process, are changing some flight numbers, but keeping the times the same. I know of others who have experienced this, as well. I proactively cancelled a reservation with a connection, as I just had a funny feeling; yesterday, I noticed that my previously-booked flights no longer exist.I got an email with the exact same change to one of my flights. I don't believe my flight was on a Max either.
Heads up, for those booked on DME. Double-check your info on your flight numbers, as they may have changed, since booking DME, and you may need to update your Magical Express flight info.