I believe that if you are going to a wedding in Poland, you should find out what their customs are.
The custom in Poland is that when the young couple invites anyone to their wedding, they have absolutely no right to expect any gift from them whatsoever. They are obligated to be effusively and eternally grateful to even those guests who do not give any gift other than the honor of their presence, which is, exactly all that the young couple is allowed to ask for in the invitation.
Any mention or talk of gifts between the young couple and their guests is considered extremely rude. Beyond the pale, regardless of who initiates it. Even if a guests asks, all the couple can respond is "Your presence is the greatest gift you can give us. Nothing more is required or expected". Full stop.
If the couple would be disappointed that a particular guest did not give a gift, it was a major breach of etiquette to invite that person in the first place. It's hard to go lower than to invite people on the presumption that they will give a gift. That is an enormous insult.
A wedding is given by the couple of their own free will to celebrate their special day with those they love, expecting absolutely nothing in return. It is not a moneymaking opportunity. No one owes them anything. They alone bear the responsibility for the cost of the wedding, of the honeymoon, and of their future life together. They cannot pass the cost on to their guests. That would be monstrous.
If anyone is kind enough to help them out of the kindness of their hearts of their own free will with a gift of the guest's choosing, the couple is obligated to thank them from the bottom of their hearts, exactly as they are obligated to thank each and every guest who shows up without a gift, or who doesn't show up yet sends their kind regards.
Pretty much the same as in any other northern European and English speaking country.
Of course, that's the ideal. In reality, people can be pigs.