Would be interesting to read that proposal, as "usage level"[1] and "compatibility with existing systems"[2] are both factors that the emoji working group officially considers for new proposals.

So if the proposal includes one or both of those sections, that could shed some light on possible former usage in "proprietary" software.

Unfortunately, I don't see the actual proposal accessible anywhere.

[1] https://unicode.org/emoji/proposals.html#Selection_Factors_U...

[2] https://unicode.org/emoji/proposals.html#Selection_Factors_C...

Interesting, I sent this comment from a client on a phone, and forgot that the emoji wouldnt show up.

What I wrote was U+1F30A U+200D U+1F40E