To be clear, this only affects exit rows that have additional leg room, i.e. row 16 on the refurbished 737-800 and 737 MAX 8, and rows 16/17 on the 737-900 and 737 MAX 9. Exit rows without additional leg room are not affected.

Also 18A/F on the refurbished 737-800 and 737 MAX 8 (which have unlimited leg room) are still Preferred rather than Premium.