Both recent flagship smarpthones from Xiaomi and OnePlus featured an optical in-display fingerprint sensor, but, according to a couple of sources on Weibo spotted by GSMArena.com, both companies are testing ultrasonic fingerprint sensors for their upcoming Xiaomi 15 and OnePlus 13 flagship smartphones. The ultrasonic fingerprint sensors are much more precise and significantly faster compared to their optical counterparts.
Both companies are still in early development days so it could be a while before we see those new smartphones as both Xiaomi and OnePlus release their flagship phones near the end of the year, at least in China, while global launch could come early next year.