What is disputed about “qablahu” in “wa-aʿlamu ʿilma al-yawmi wa-l-amsi qablahu”?

Ījāz, Iṭnāb and Musāwāt: Standards of Expression and Their Distinctions

• Whether it changes a past verb into the imperfect
• Whether it removes a circumstantial conjunction
• Whether it repeats an existing time relation or strengthens the contrast
• Whether temporal qualifications after yesterday are forbidden