Yes it has because the national minimum wage in Poland increases regularly and your contract must match or exceed the current legal threshold. If your earnings are too low the inspector will simply reject the application regardless of other documents. Detailed info on https://immigro-legal.pl/service/karta-pobytu-trc/ helps you calculate if your gross salary meets the current requirements for the single permit. It is a good idea to ask your employer for an annex to the contract if your pay has not been adjusted to the latest regulations yet.