Yovel

only if effect when all tribes are living in Israel on their ancestral portion, therefore not in effect in our times

smaller than four amos by amos isn’t considered a house, exempt from mezuzah, fence requirements, contributing to eruv chatzeros, maaser laws, can’t serve as a extension to a town in regard to eruv techumin, vows regarding enjoying houses, loading and unloading rights by front door, Yovel laws, tzora’as of houses, returning during war based on an unused house

sold ancestral field on the Yovel year, sale valid and land reverts to owner immediately, or sale void?

stopped being in effect once the tribes were no longer all living on their ancestral lands (first temple era)

when Yovel isn’t in effect, shemittah is a rabbinic law (not a biblical requirement)