I did find that troubling too. I can see the logic of a short lived / well funded project using nextjs, but for something like this that's meant to be a simple form that needs to be reliable, easy to maintain, and long lived, my first thought would be to make a classic restful MPA. Introduction of a complex frontend framework like next seems like it would lead to more headaches than it's worth. Had similar thoughts about the Azur vendor lockin. I seriously doubt they had the traffic to justify needing something like Azur functions and batch processing. I'd love to hear some more justification for why they choose this stack, and if they considered any alternatives first.
If it was really down to two engineers, it's almost certainly what one or both of them were already comfortable or familiar with and no other reason. Six months is such a short time frame for long term projects like this that I imagine they could not spare much time for analysis of alternatives.
If you're comfortable with nextjs, you should be even more comfortable with a nodejs SSR application. It's the same thing, but simpler. The HTML doesn't even have to be pretty. We're really just querying a DB, showing forms, and saving forms. Hell, use PHP if you want.
