To correct what you wrote, they were found in a warehouse at a bottling plant, not a harbor, and half of them were COVAX shots that had been produced by the South American supply chain and had just come through Europe for bottling and QC.

The other half were EU shots - held back because the EU had not yet given regulatory approval to the bottling plant.

The allegation, made by un-named sources, is that AZ were deliberately delayed this regulatory approval, presumably by being slow to file paperwork. As there is obvious hostility towards AZ, it is also possible factors on the EU side were causing a delay.

I would say that, having raided a factory with great fanfair looking undeclared stockpiles, saying you found one, and then discovering it was declared and all above board, one way out of the PR problem would be to anonymously make an allegation like that. On the other hand, maybe it's true. Who knows.

With that said... once you start thinking AZ are secretly holding vaccines back to smuggle out of Europe like some Columbian cartel, you are well into QAnon teritory. They would be risking a lot to do that - they are already facing so much for failing to meet a contract, actually smuggling drugs would destory the company. Why would they do it?