It’s not that bizarre. A teenager’s intellectual and emotional maturity grows exponentially in HS. One is likely more developed in many respect junior year than sophomore year. There may be valid reasons for choosing a sophomore teacher. For example, Stanford says:
https://admission.stanford.edu/apply/freshman/evals.html
When all else fails, read the what the college asks. A teacher rec generally means a person who has taught you, not a person who happens to be a teacher. If the department chair has not taught you, you can use the rec as a supplemental rec if the college allows additional recs.