Abandoned, Banished, Expelled, or Exiled

MC quits his job after being mistreated for being a commoner. So he gets a new job in the meritocractic Empire. (And you're not gonna believe this) It turns our that MC is actually pretty useful and powerful.

After defeating the Demon Lord, the hero MC gets betrayed by his party and his accomplishments diminished. So he goes back to his hometown to live a peaceful life.

MC gets kicked out of his party for being old and stripped of his adventurer's license. Later, MC starts a new life of traveling after meeting a cursed girl.

MC quits his job after being treated like a slave for having weak magic. It turns out that his long-duration E-rank magic is actually really convenient and profitable.

MC gets banished from his party for being a useless errand boy. MC starts a new journey and turns out he has hidden potential as an alchemist.

MC is a butler who gets mistreated by his lady. So MC flees over the border to a neighboring meritocratic Empire. MC enrolls in a vocational school and it turns out that he's really skilled as a butler.

MC is a court blacksmith who gets bullied by his colleagues. He then gets scouted and engaged by a duke's daughter to work for her family. It turns out that MC is a really talented blacksmith.

MC is a maid who gets fired for "seducing her master". So she finds new employment in the countryside as a maid for an unsociable magician.

MC gets sent as a hostage to an enemy country because she has no charm or charisma. Turns out MC is actually valued there for her incredible book-smarts.

MC gets mistreated and left for dead in a dungeon by her party. So she starts a new life as a "housekeeping mage".