-losing 20 lbs in 3 weeks is not typical, and despite starting from a decently heavy bodyweight, I would worry a bout dropping so quickly if your goal is to indeed look good, and not just weigh less.
-2400 calories is very low for your current weight. Even if you’re trying to focus on maintaining LBM and not just ‘weight’, or a 500+ cal deficit, that’s alarmingly low IMO. As others have mentioned, you can’t just keep dropping, so jumping too low too soon will hurt your overall progress in terms of slowing your metabolic rate.
-You can build muscle while visually tightening up (recomping), but understand that in such instances, you may not be able to rely on scale readings to register a complete picture of your progress. Ideally, you could be eating more, losing scale weight at a much slower pace, and building muscle with a well thought out overall program.
S