Had to to do a bit of research on servo wave. Apparently its been around for a while. It goes back to the ugly RS505 shifters.
the list of servo wave shifters can be found here:
The ultegra R8020 and R8025 (short reach) shifters have servo wave as well. and the grx 810 and above models.
If anyone has experience with how the servo wave shifters please let me know.
Hope it helps