The Frenchman left Everton for Marseille on a season-long loan last summer.
And after Everton's defeat to Nottingham Forest, Maupay posted to social media: "Whenever I'm having a bad day I just check the Everton score and smile."
Everton now sit in 16th place on the Premier League table, three points from the dropzone.
After a threatening response from Everton fan and boxer Tony Bellew, Maupay posted: "See you in the Championship next season!"