The phrase "most into" refers to being highly interested or invested in something. Antonyms for this phrase could include "least interested," "apathetic," or "unengaged." If someone is "least interested" in something, they have no strong feelings or enthusiasm towards it. If they are "apathetic," they lack any emotion towards it altogether. And if they are "unengaged," they simply have not committed any time, effort, or resources towards it, without necessarily feeling any particular way about it. These antonyms suggest a lack of enthusiasm or investment, essentially conveying the opposite of what it means to be "most into" something.