What to do if I didn’t get any stamp when I entered Poland?

If you are a person covered by the Act on assistance to Ukrainian citizens (see here: https://ukraina.interwencjaprawna.pl/the-act-on-assistance-for-ukrainian-citizens/ ), your entry into Poland has not been registered during the inspection, then you can Register by submitting an application for a PESEL number. You have 90 days to do so from the date of entry into the territory of Poland.

Legal basis (April 26, 2022): The Act of March 12, 2022 on assistance to Ukrainian citizens in connection with an armed conflict in the territory of that country (Articles 3 and 4).