With the change to activity-aware favorites the "Add to Favorites" and "Remove from Favorites" context menu entries on apps moved to the top, even above jump list actions, drawing a lot of attention to it. It should be at the bottom again like it used to be.
I cannot reproduce this on 5.13.4; "Add to Favorites" is always at the bottom in the context menu, also when two Activities are active.
Fixed that without closing this bug :) [1] [1] https://cgit.kde.org/plasma-desktop.git/commit/?id=55eabda75ae6c43d7d7d88fbbac5fdbfe1003c34
:-)