Hello  @David-TP,
don't take it personal, I am so sorry to push but I wonder whether we're gonna get an update any soon or I can start boxing and returning the XE75 Pro.

Thank you.

All the best,

Andrea  

I have just upgraded my Deco XE75 Pro V3.0 with firmware 1.4.0 https://community.tp-link.com/en/home/forum/topic/856648?moduleId=39 and ECO Mode is finally available on the device.