Wobbly/loose keycaps on MacBook Air M1

Sounds like it's a new Mac? If that's the case, I'd highly recommend bringing it in to an Apple Store. If it's a simple fix, they can take care of it while you wait.

Just so you're prepared, though, I'd suggest making sure you have a Time Machine backup that's updated before bringing it in. In the event Apple has to swap out parts, it's best to have that backup in the event Apple puts your Mac back to factory condition.

I've no idea why the keycaps aren't secure. It's possible, though, that the Apple tech may have more insight on this for you when you take it in.