I read that a peasant in the middle ages typically worked less and had much more leisure than a worker in the 21st century.

Peasants in the Middle Ages did hard, agrarian labor, had poor sanitation, high child mortality, and limited horizons. While nobles had wealth and comfort, the era was generally harsh, with most lacking modern amenities and facing short, physically demanding lives.

You can achieve medieval peasent level of life quality by not working at all these days.

You've read that they had more days off but that's only because they couldn't work in the winter.

Instead, they hoped the food stores would last and the kids wouldn't die so they could help work the land next year.