Great news, we're bringing the plague back too!

Specifically, the peasants had more bargaining power for better conditions because the absolute decrease in their number made each of them more valuable to the ruling class as individuals. There was an increase in peasant revolts and concessions to the peasantry following the black death partly for this reason.

This is true in places. There are also acounts of places where all the nobility died and the peasants threw weeks long parties.

Yup, labor scarcity meant higher wages and bargaining power.