This case involves Maine's tuition voucher program, where Maine excludes vouchers to parents who wish to send their kids to religious schools. Oral arguments were fascinating. Justice Thomas asked the attorney for one of the plaintiffs about standing, which I thought he argued well. Best I can tell, the argument is over whether the denial of funds is because of the school's status as a religious school or whether it is because the money would be used to teach religion.
Given general trends, I expect the plaintiffs will win this one, but as ever, Thomas on standing, or Roberts or maybe Gorsuch on other grounds, could be a wild card.