That's unpredictability is why it's on my Honorable Mention rather than the Top Ten proper
(2/5/2021) If an effect causes a creature with changeling to become a new creature type, it will be only that new creature type (unless the effect says "in addition" or similar)
I think where it becomes the most dangerous is when a card is creating a huge blast of Treasures that come into play untapped. "I could definitely see a world in the future where we try and make the big blasts of Treasure come in tapped." Most experienced Commander players probably wont be surprised to hear Verheys example of this: Dockside Extortionist , a creature from Commander 2019 that can produce boatloads of Treasure, poetically blasting its own price on the secondary market to more than $60USD at time of writing
Firstly, we have the Moxen
You want to get rid of Chromatic Stars, Ichor Wellsprings, and Experimental Synthesizers, making this a no-brainer removal spell in many decks
When in doubt, check the Oracle Text online