Y'know Sans is supposed to represent an extremely hard boss where the only goal that Sans has is tempt you to Reset the game so you can't go forward. But once you master Sans it kinda feels obscure and it takes that sense of difficulty away and it almost feels meaningless...

Tbh I always found undyne the undying harder Maybe it’s because I grew up with a lot of platformers.

Jevil is still harder than both of them though easily I’d say that Jevil reaches the same difficulty of Inner Agent 3 and Mustache Girl EX