Tensai Rekinjutsushi Wa Kimama Ni Tabi Suru summary:

The youngest girl ever to become a court alchemist, Seyi, was busy with hard work every day. One day, the royal city was suddenly attacked by a horde of monsters, she woke up 500 years later. The city had already been destroyed, and Seyi, freed from her hard work, was determined to travel through a completely changed world. She was supposed to travel freely, but her potion-making skills quickly become the talk of the town?!The genius alchemist's leisurely, slow-life journey begins!(from mangaupdates)