It's unlikely to be an issue. Off campus rent and food are eligible expenses for a 529 distribution, but the amount is limited to the lesser of your actual cost or what the school charges on campus students for R&B (technically the schools "allowance for cost of attendance" for financial aid purposes). The IRS will most likely accept the school's number.
https://www.glassjacobson.com/blog/529-off-campus-housing/ Excellent off campus explanation
