I had a temporary residence permit in Poland for the last 5 years due to my ongoing studies - can I already obtain a long-term resident's EU residence permit?

If you are now staying in Poland on the basis of a temporary residence permit due to your studies and file an application for a long-term resident of the EU, the proceedings will not be initiated.

Remember also that in the future the period of stay in Poland due to studies will be counted only in half.