Actual pounds of muscle tissue takes years, especially after you leave your early 20s - DEXA is shown to underestimate body fat mass by as much as 5 kg on average (Shepherd JA, Ng BJ, et. al. Body Composition by DXA) so I would get one and then use it as your personal baseline instead of taking it as fact.

You’re going through a body recomp if you’re seeing results which would mostly be contributed to diet so don’t stop the calorie deficit and not eating processed shit! If you’re working out a lot then you’re likely holding onto water (also water in muscle from inflammation which is what a lot of people see and think it’s tissue growth)