According to OnePlus, one of the reasons why they ditched the headphone jack was in favor of larger batteries. Now according to an interview with CNET, OnePlus CEO Pete Lau revealed that the in-display fingerprint sensor was the other reason why they dropped the headphone jack.
Lau claims that because they had to move the sensor from the back of the phone (where it previously existed) to inside the phone, certain compromises had to be made and the headphone jack was one of the casualties. Lau also adds that this was a very hard decision for them to make, especially since OnePlus used to be one of the few Android OEMs who had stuck with the 3.5mm headphone jack while everyone else was removing them.
According to Lau, “This has been one of the most difficult decisions for us to make. The most difficult task in the day-to-day is… finding a balance in what’s ultimately going to be part of the end product and what has to be said ‘No’ to.” The OnePlus 6T is currently set for a reveal on the 17th of October.