This is the question that ties into mine — if the economic incentives have changed (i.e. there is no penalty for renters of containers to not get containers back to their primary shipper) then this is a perfectly reasonable response to the change from Covid to today — i.e. the new game is moving the ship as fast as possible with no downtime. If the demurrage is still incurred, then there’s some other alternatives that do not appear to be completely without nefarious intent.
If a single extra trip is lucrative enough and at current rates it’s 5-10 regular prices that would make sense to forgo loading in the us and just hurry home
It might be other forces driving their decision. Maybe the ships are booked and are already late to pickup next load with penalty clauses for delay, or the port has other costs that mean it wants to speed up getting the next ship unloaded.