Can I enter and leave Poland with an extended visa due to the epidemic situation?

It depends on the type of visa. National visa holders retain the right to cross the state border and stay on the territory of the Republic of Poland during the epidemic/epidemic state, and for a period of 30 days after the last state is revoked. You can legally leave Poland straight to your country of permanent residence and come back to Poland, there will be no possibility of transit, e.g. from Poland via German, on extended visa.

For details check here: https://udsc.gov.pl/en/cudzoziemcy/coronavirus-outbreak/