https://www.cnet.com/news/oneplus-7-teased-in-fast-and-smooth-oneplus-tweet/

Because Lau reference "smooth" multiple times, he could be hinting at a few rumors that already surround the phone. There is speculation that the phone's display will curve down at its sides like high-end Galaxy phones. The phone is also rumored to have a pop-up camera, which would smoothly rise from the top edge of the phone. In any case, "smooth" is a pretty generic word to use and Lau could also just be saying that the phone's performance is smooth.

The latest batch of rumors report that the phone will launch May 14. In the meantime, all we'll have to go on officially is Lau's enthusiastic tweet.