Created subject id=27, name=TEST_SUBJECT_1775179496, teacher_id=2
Inserted pivot row for teacher_id=2, subject_id=27
Current teacher_subject rows for subject 27:
 - id=77 teacher_id=2 subject_id=27 created_at=2026-04-03 09:24:56
After setting subject.teacher_id = NULL and deleting pivot, rows for subject 27:
 - none
Deleted test subject 27