Wouldn’t entire thread need to be light green. Wouldn’t android users not see the Tapbacks/threads in same visual UX. It makes sense to turn it off entirely than to deliver a subpar and confusing UX
As for reply threads, when it's used it creates a lot of confusion for non iPhone users and it's not clear how Google Messages and other texting clients can fix it post-hoc. I'm not even sure how iOS reconstitutes it-- perhaps Apple sends some message metadata on the side via iMessage?
Hopefully the experience is improved when they implement RCS, though I'm not sure if tapbacks are part of the spec.
Unless there's something I'm missing, only Android users get cross compatible tapbacks.