Sforno on Leviticus 22:9/ספורנו על ויקרא כ״ב:ט׳

1אני ה' מקדשם, I have sanctified them (the items sanctified as donations by the ordinary Israelites) It is therefore appropriate that priests who treat these sanctified objects with disdain (as if they were profane), be punished for desecrating them.