This is Swift Light, a Substratum theme. The idea with this theme is to make apps all light. It's inspired by Android O and Samsung, and you use it with the Substratum theme engine. It supports Nexus & Pixel / OxygenOS Nougat / LineageOS / Samsung S8 / OMS / Oreo 8. 0 / Oreo 8. 1 / OxygenOS Oreo.