「HSR 4.7」 About Ex-Eidolon
Ex-Eidolon will be added in near future test version, currently data says there will be additional slot in eidolon page, unlocking via new material.
Three characters will have buff and UI animation changes, detailed buff you can check in https://t.me/Seele_Leaks/36801 (detailed stats are unknown but you can check Sakura's post for old sus leak)
Also there is an activity which you can select one of these characters, similar like Gilgamesh or 4.0 character given activity.
It indicates one of the Ex-Eidolon will be given.

ALL STUFF IS STC