Poland could easily be drawn into this war by accident. Military supplies are being shipped into Ukraine from Poland and Germany. Soon, from the entire EU. Russian attempts to stop those might spill over the border into Poland, possibly by accident. An air attack overrunning the Polish border and being shot down by the Polish air force could happen very easily.
Poland is a NATO country. An attack on Poland within its borders activates NATO's mutual defense agreement.
Review how WWI started.