To my knowledge, MDF warps with moisture and heat. So she was super smart to put so much of it next to a roaring fire in a kitchen where steam from cooking will be floating around, let alone putting moisture-creating appliances inside of it.
There are ways you can make them a bit more resilient, like putting wallpaper paste on them to create more of a barrier or using bathroom paint instead of kitchen paint, but a) that wouldn’t be as aesthetic for Lady Maddie, and b) for a YouTuber who makes most of her money off of ‘renovation’ content, she seems to be allergic to putting any effort in at all and just complains like a child when it obviously goes wrong afterwards.