Poland is supposedly bound by a contract the terms of which it does not know. From Igor Chudov at igor-chudov.com:
I think that Poland should SUE PFIZER
After achieving a modest 57% COVID vaccination rate and seeing the vaccines not live up to the promise, Poles refused additional Pfizer COVID vaccine doses around April 2022.

“At the end of last week, we used the force majeure clause and informed both the European Commission and the main vaccine producer that we are refusing to take these vaccines at the moment and we are also refusing to pay,” health minister Adam Niedzielski told private broadcaster TVN24.
“Indeed, the consequence of this will be a legal conflict, which is already taking place,” he said.
Poland cannot directly terminate the contract for the supply of vaccines as the parties to the contracts are the European Commission and manufacturers, he said.
The value of the contract for vaccine supplies to Poland up to the end of 2023 with one producer alone was worth over 6 billion zlotys ($1.4 billion), with over 2 billion zlotys of that for supply in 2022.
Pfizer said its agreement over the supply of its COVID-19 vaccine to European Union member states was with the EU Commission.
“Our discussions with Governments and the details of vaccine deliveries are confidential,” it added.
Somehow, Poland is a party to the EU/Pfizer contract that was kept confidential from the country but still obligates it to pay.