There definitely seems to have been a point in Early Access where they started drastically scaling back features. Paladin Deities getting hastily stripped out shortly before the release of the class, Minsc getting stripped of Origin character status and shove back from an Act I recruit all the way to Act III. But there seems to have been some particularly drastic stuff going on right before release. A lot of stuff getting hyped right up until release. Pretty sure Minthara was still getting hyped up as a romance option in the last one or two videos from Larian, only to get almost all of that cut by release day....quite a lot of content if the determiners are accurate.
Lots of big stuff. Lots of small stuff got removed. Honestly I have to say I enjoyed EA Act I more than release Act I. Narratively, the character interactions, etc, just the amount of content that's now lost.
I am starting to feel that despite the long EA and development time that BG III was more than a little rushed out the door to meet a date near the end of development. Why else would stuff like the districts of BG or the Minthara romance still be getting talked about by the devs right before release?