Vivo has just released a new promotional poster showing what it is calling the U3, above which the number 675 can be seen. The device in question may be the V1934A/T, which has reportedly passed through TENAA's testing. The new image of the "Vivo 675" phone resembles this unit as shown on this website closely.
https://www.notebookcheck.net/Vivo-teases-the-U3-a-new-Snapdragon-675-powered-phone.439834.0.html