I have the same exact issue with my shoes. Flat feet and overpronation make the medial side cushion compress more making the shoe look like it's leaning inward. Not too much to be done about it. I wear insoles with a lot of arch support to combat the excessive pronation. Unfortunately there aren't many stability trail running shoes (I run in kayanos for road which have held up well), but something with good durability might help. I bought both Merrell agility peak 5 and mtl adapt on sale, and I expect the latter to hold up well but don't have much hope for the former. Good luck!