As far as I know, all of the following stores take a 30% cut:
* Steam * GOG * Microsoft store * Xbox store * PlayStation store * Nintendo eShop * App store * Play store * Kindle store
There's also stuff like Audible where Amazon takes a 75% cut unless you agree to exclusively sell your audiobook through them. And there was a lawsuit over that because it turned out Audible was actually only paying authors a 15% cut, while keeping 85% of sales for themselves.