Incorect display when useing VS-15 text selector

[ChiefMikeK]

Maybe need a build-test for this?
Noto Emoji Medium v3.0030060 (2024-08-10)

🙂‍↔ 🙂‍↔︎ 🙂‍↔️ Head Shaking Horizontally
🙂‍↕ 🙂‍↕︎ 🙂‍↕️ Head Shaking Vertically 

[jbicha]

Could you use more words to explain exactly what steps are needed to reproduce this issue, what you experienced, and what you expected?

[kenmcd]

Clear as mud. 🙂.
Have to see what is happening in the application being used.
Which I am guessing is a browser.
Noto Emoji only has black (text) emojis, so not sure what the variation selector should do.
Maybe you know more about emoji fonts than I do.
And/or can guess better.

First test line above (I added a few blank lines to clarify):

U+1F642 : SLIGHTLY SMILING FACE
U+200D : ZERO WIDTH JOINER [ZWJ]
U+2194 : LEFT RIGHT ARROW {z notation relation}
U+0020 : SPACE [SP]

U+1F642 : SLIGHTLY SMILING FACE
U+200D : ZERO WIDTH JOINER [ZWJ]
U+2194 : LEFT RIGHT ARROW {z notation relation}
U+FE0E : VARIATION SELECTOR-15 [VS15] {text variation selector}
U+0020 : SPACE [SP]

U+1F642 : SLIGHTLY SMILING FACE
U+200D : ZERO WIDTH JOINER [ZWJ]
U+2194 : LEFT RIGHT ARROW {z notation relation}
U+FE0F : VARIATION SELECTOR-16 [VS16] {emoji variation selector}
U+0020 : SPACE [SP]

U+0048 : LATIN CAPITAL LETTER H
U+0065 : LATIN SMALL LETTER E
U+0061 : LATIN SMALL LETTER A
U+0064 : LATIN SMALL LETTER D
U+202F : NARROW NO-BREAK SPACE [NNBSP]
U+0053 : LATIN CAPITAL LETTER S
U+0068 : LATIN SMALL LETTER H
U+0061 : LATIN SMALL LETTER A
U+006B : LATIN SMALL LETTER K
U+0069 : LATIN SMALL LETTER I
U+006E : LATIN SMALL LETTER N
U+0067 : LATIN SMALL LETTER G
U+202F : NARROW NO-BREAK SPACE [NNBSP]
U+0048 : LATIN CAPITAL LETTER H
U+006F : LATIN SMALL LETTER O
U+0072 : LATIN SMALL LETTER R
U+0069 : LATIN SMALL LETTER I
U+007A : LATIN SMALL LETTER Z
U+006F : LATIN SMALL LETTER O
U+006E : LATIN SMALL LETTER N
U+0074 : LATIN SMALL LETTER T
U+0061 : LATIN SMALL LETTER A
U+006C : LATIN SMALL LETTER L
U+006C : LATIN SMALL LETTER L
U+0079 : LATIN SMALL LETTER Y

Second test line above (again added some blank lines):

U+1F642 : SLIGHTLY SMILING FACE
U+200D : ZERO WIDTH JOINER [ZWJ]
U+2195 : UP DOWN ARROW
U+0020 : SPACE [SP]

U+1F642 : SLIGHTLY SMILING FACE
U+200D : ZERO WIDTH JOINER [ZWJ]
U+2195 : UP DOWN ARROW
U+FE0E : VARIATION SELECTOR-15 [VS15] {text variation selector}
U+0020 : SPACE [SP]

U+1F642 : SLIGHTLY SMILING FACE
U+200D : ZERO WIDTH JOINER [ZWJ]
U+2195 : UP DOWN ARROW
U+FE0F : VARIATION SELECTOR-16 [VS16] {emoji variation selector}
U+0020 : SPACE [SP]

U+0048 : LATIN CAPITAL LETTER H
U+0065 : LATIN SMALL LETTER E
U+0061 : LATIN SMALL LETTER A
U+0064 : LATIN SMALL LETTER D
U+202F : NARROW NO-BREAK SPACE [NNBSP]
U+0053 : LATIN CAPITAL LETTER S
U+0068 : LATIN SMALL LETTER H
U+0061 : LATIN SMALL LETTER A
U+006B : LATIN SMALL LETTER K
U+0069 : LATIN SMALL LETTER I
U+006E : LATIN SMALL LETTER N
U+0067 : LATIN SMALL LETTER G
U+202F : NARROW NO-BREAK SPACE [NNBSP]
U+0056 : LATIN CAPITAL LETTER V
U+0065 : LATIN SMALL LETTER E
U+0072 : LATIN SMALL LETTER R
U+0074 : LATIN SMALL LETTER T
U+0069 : LATIN SMALL LETTER I
U+0063 : LATIN SMALL LETTER C
U+0061 : LATIN SMALL LETTER A
U+006C : LATIN SMALL LETTER L
U+006C : LATIN SMALL LETTER L
U+0079 : LATIN SMALL LETTER Y
U+0020 : SPACE [SP]

So it appears he is expecting different results from each of those sequences.
But if it is just a black font, does that make sense?

[ChiefMikeK]

https://www.unicode.org/reports/tr51/#Emoji_Variation_Sequences
The first collum should render in a word processor, text editor, terminal, ect. the same as in the second collum!

With recent updates to this font these two code points added in UNICODE 15 the ↕ and ↔ are FALLBACK diplayed in the second collum.