A lot of this has to do with more kids going to private and charter schools.

Look at all these relatively new charter schools. https://www.education.nh.gov/who-we-are/division-of-educator-and-analytic-resources/bureau-of-educational-opportunities/charter-schools/approved-public-charter-schools

They are also growing rapidly https://www.nhpr.org/education/2022-11-29/nh-charter-school-enrollment-increases-14-percent-in-past-year?_amp=true