Tankers may wait for paperwork as well as berth space

Why might several Chinese tankers wait off Malta before docking?

They may be completing paperwork after changed voyages or waiting for limited berth space, not necessarily delayed by the oil purchase contract alone.

A cluster of tankers at anchor does not identify a single commercial cause by itself. Ships diverted by changing world events may need revised documents before entering port. Berth congestion can also keep vessels waiting even after cargo and payment arrangements are settled. Visible anchorage delays can combine legal, commercial, and physical port constraints.