What does it mean when a conference submission system asks if the first author is a student? When I recently submitted a paper to a conference, there was a checkbox asking whether the first author is a student. Did you encounter anything like that? Does this means the reviewers will consider this and will be less strict?
It can mean lots of things and only the conference organizers can tell you the reason. There could be student paper awards, travel awards, or student presentation sessions. There could be research speed dating or a desire to have more student presentations in each section.

Likely the peer review will not change, but the selection process might chnage. Paper selection is not just about the best paper, but about the best fit given the goals of the conference.