OPPO has now confirmed that its premium Find X3 smartphone series will launch on March 11, 2021. Its flagship, the X3 Pro, is now rumored to have a display panel that combines the high-end E4 AMOLED and LTPO specs. However, it will allegedly also start for less than a Samsung Galaxy S21 Ultra with the same amount of internal storage.
https://www.notebookcheck.net/OPPO-Find-X3-Pro-a-flagship-with-the-best-possible-Samsung-display-yet-cheaper-than-a-Galaxy-S21-Ultra-according-to-new-leaks.526439.0.html
Hmmm, so despite Samsung first fielding the substrate, they're not the first to advertise it. :)
And the apparent E3, E2 and E1 before it were never advertised either.