The Netziv says that Matzos are similar to Menachos which can’t have Chametz or: שְ אוֹר (leavening agent). שְ אוֹר (leavening agent) symbolizes the: תַ חְ בּוּלוֹת strategies of an Adam to enhance the dough and make it rise. The Bais Hamikdash is a place of: הִ תְ קַ רְ בוּת לַ ה' coming close to Hashem, and such a person needs to be: מְ מַ עֵּ ט (minimize) in תַ חְ בּוּלוֹת strategies and bring a plain Matza (similar to having Bitachon without doing Hishtadlus).
We can suggest that’s why the Korban Mincha is related to the word Menucha (Meforshim) since the (chametz free) “Mincha” is similar to Bitachon without Hishtadlus, and loads of Menucha without worry that Hishtadlus brings. And Pesach is a Zman of Ahavas Hashem (Shir HaShirim is read), similar to the closeness to Hashem of the Bais Hamikdash, and that’s why we stay away from “chametz”. (Netziv).
