It seems like there's a logical series of events here: when animating Maud's first appearance, the animators used the pre-existing Flash symbol for Tom, in lieu of there being any predetermined official mark. Then the toy design team was tasked with making a Maud brushable, and Googles "maud pie cutie mark," where they end up finding the gem mark, and assuming that's it. Enterplay follows suit, possibly referencing the toy or their own search. You'd think Hasbro would have oversight at some point and say, "hey that isn't her mark," but it may be the case that therean official mark for her - just what the animators decided to use vs what the toy makers did.So, yup, that all boils down to show-canon vs merch-canon.It'll be interesting to see if it's ever visible in the show again, and if they switch it out, or keep it Tom.