Two separate sources speaking with TechCrunch confirmed that Pei has left OnePlus.
According to the report, Pei is starting "a new venture" and "is in talks with investors to raise capital.
Pei's Twitter bio still reads "#NewBeginnings @oneplus" and his LinkedIn profile still lists him as a co-founder of OnePlus.
Pei was looking after the successful OnePlus Nord lineup and previously the flagship models from OnePlus.
Emily Dai, who is currently in charge of the company's operations in India, may be appointed as the head of the Nord product line globally.
Pei and Pete Lau started OnePlus back in 2012 and have led the company from a tiny smartphone brand to one that leads in several markets, including India.
A few months ago, Lau was reassigned to look after product development and planning for Oppo, Realme, and OnePlus.
OnePlus 8T 5G is set for a global launch on October 14. It will run OxygenOS 11 based on Android 11 and comes with 120Hz refresh rate.
The OnePlus 8T will succeed the OnePlus 7T that launched in India in September 2019.
The device may feature a 6.55-inch AMOLED display just like the regular OnePlus 8.
The smartphone is expected to come with four cameras at the back, with a 48MP primary lens joined by a 16MP wide-angle module, 5MP macro, and 2MP portrait lens, according to the report.