[4] Both the OnePlus 9 and 9 Pro use the Snapdragon 888 processor with the Adreno 660 GPU, with either 128 or 256 GB of non-expandable UFS 3.1 storage.

The main upgrade is in the optics and color processing, which were co-developed with Hasselblad, specifically in the ultra-wide camera.

[9][10] An investigation by AnandTech revealed on July 6, 2021, that the OnePlus 9 and 9 Pro throttle the performance of popular apps by limiting them to the processor's slower cores.

As a result, benchmarks in apps such as Google Chrome performed up to 85% slower than competing phones that use the same Snapdragon 888 processor, such as the Samsung Galaxy S21 Ultra and Asus Zenfone 8.

When running the same benchmark in the Microsoft Edge web browser, which is not throttled, the 9 Pro outperformed the OnePlus 8's Chrome result by about 7%.

[12] The next day, OnePlus admitted in a statement to multiple news outlets that it was throttling the performance of as many as 300 popular apps, claiming the decision was made after complaints from users about battery life and overheating issues with the devices.

[13][14] Multiple outlets criticised OnePlus for introducing the throttling feature without informing device owners.