I'm a college (physics) professor, and last semester specifically had a huge shift in student behavior. In introductory courses, students basically stopped coming to help sessions.

I give a substantial amount of extra credit for attending regular help sessions which yielded about 30% help session conversion in past semesters. This term it dropped below 5%, and those few who came were the ones who were high B/ low A students. The solid A students don't come because they don't need to. The low B and lower students didn't come because they thought they didn't need to? It's unclear, but clearly something changed.

Students performing in the mid-B and up range weren't affected, but below that? The bottom dropped out. Students who should have earned B's earned C's. Students who could have earned C's... didn't.