Xiaomi's Mi Mix 3 is probably coming this September, as past rumors and leaks have told us. It is expected to push the screen-to-body ratio even further than its predecessors, which is useful for the company in a world where the vivo NEX S and Oppo Find X exist. The Chinese smartphone maker may have accidentally leaked the design outline of the upcoming Mi Mix 3 itself, through the MIUI 10 release that went out to other phones. There used to be a screenshot inside the software that shows a Xiaomi device with a dedicated AI button on the left side. Such a product hasn't been launched...
Source: https://www.gsmarena.com/xiaomi_mi_mix_3s_design_might_have_been_leaked_by_miui_10-news-32473.php
