Which Unicode for Pi?

[Spammed]

I'm sure there's a good reason.
I'm curious as to why the decision turned out the way it did.

Greek Small Letter Pi “π” (U+03C0) vs. Mathematical Italic Small Pi “𝜋” (U+1D70B)

[mpusz]

We had a discussion about it with SG16 (Unicode group in WG21) and they claimed it is the way to go. The also correctly pointed out that:

ISO 80000-2:2019 Quantities and units Part 2: Mathematics, whose Clause 4 says that mathematical constants and functions that do not depend on context are in upright type, and explicitly gives the example of π.

[Spammed]

Thank you. I've learned something again.