According to a new report, Xiaomi has overcome the issues that ZTE experienced with making an under-display camera invisible to the naked eye. Supposedly, the technology will arrive in the Mi Mix 4, albeit possibly with hamstrung image quality.
https://www.notebookcheck.net/Mi-Mix-4-tipped-to-debut-with-an-almost-invisible-under-display-camera-in-a-trade-off-over-image-quality.549576.0.html