We took a HUGE hit this year in numbers. We didn't get to test any students in person that were in 5th last year (which I find helps with retention and recruitment). We also had a lot of former beginners either start or end up virtual, and they lost all interest in band. So, this year we have around 50 in our concert ensemble, and only 25 beginners.
Our program was on a growth path until this year, when we lost a lot. It looks like (so far) next year's beginner class will also be very small, even though our school population is increasing. I'd say in a typical year we usually have around 100-120 students in grades 6-8, which is around 1/3 of the school population. We have a very small amount of 7th/8th beginners, but the vast majority are 6th grade students.
Our biggest struggle for 6th->7th is athletics. Many students decide they want to pursue that instead of band because...reasons. We usually have a really good retention rate- IF we get to test students. I usually have 80-90% or higher. A couple years back I only lost 1 beginner. We've also had staff change every other year, so it's hard to keep retention up when things keep changing.