You might know that OnePlus is an Oppo subdivision, with many of its devices sharing the same design and internals as Oppo products. While OnePlus tried to deny its close ties to Oppo in the early years, the business is increasingly more open about its relationship with its parent company. That becomes even more apparent now that OnePlus has announced that it will use a custom version of Oppo's ColorOS in China in favor of its own China-only HydrogenOS.
The announcement comes courtesy of Gary C, the lead developer of OnePlus's global Android skin OxygenOS. Gary C specifically talks about a "customized version of ColorOS, tailored specifically for OnePlus smartphones, starting with the upcoming OnePlus 9 series." However, there are no plans to make ColorOS the default internationally: "For all of our users outside of mainland China, we will continue using OxygenOS for global devices in the future and remain committed to offering a fast and smooth experience with OxygenOS."
The decision to switch to ColorOS in China has been in the making for a while, with XDA citing an internal note saying that OnePlus's HydrogenOS website was shutting down on March 24 this year. However, OnePlus is committing to maintaining and updating currently available phones with HydrogenOS builds, so nothing seems to be changing for customers with existing devices in mainland China at the moment.
From a business standpoint, the switch to ColorOS makes sense — OnePlus won't have to maintain two separate Android skins anymore and can focus on improving OxygenOS, all while saving some resources. We might be looking at even more consolidation moves, given that OnePlus and Oppo only recently announced they were combining more of their research & development efforts.