Loading Color Emoji glyphs fails

Hello,

When I open an SVG containing an emoji in gwenview, it doesn't show the emoji, as provided by Noto Color Emoji font.

Steps to reproduce:

1. Ensure that Noto Color Emoji font is installed and is active. Maybe, it's in the package called fonts-noto-color-emoji.
2. Open a terminal to see the error messages.
3. In the terminal, execute gwenview deleteghost.svg (file attached).
4. Zoom in to redraw the image.

What's expected:

1. A ghost emoji inside a reddish litter can.

What actually happens:

1. The reddish can is drawn, no emoji inside (don't joke that it's a ghost emoji).
2. The error messages appear after each image refreshing: load glyph failed err=24 face=0x5630dfeb3a80, glyph=615. The face value differs every time I start gwenview, so, I consider it something like a memory location.

Investigation

The issue looks like https://bugreports.qt.io/browse/QTBUG-64920. However, it's not that the glyph appears elsewhere, but the glyph apparently fails to render at all.

Initially, I thought it's a gwenview bug. So, I tried the newest Qt I could find. I used the picture in a Qt 6.4.1 application. The result was the same: no emoji, the error messages instead.

When I disabled Noto Color Emoji font, gwenview drew the reddish can and a rectangle (a tofu for a missing glyph) where the emoji should appear. No errors were listed.

Many of the fonts I have installed, miss the emoji. Some (e.g., Symbola and Unifont), however, have it. Still, gwenview displayed a tofu, with no error messages. Maybe, I should have refreshed the font cache somehow better than fc-cache --force.

Finally, I disabled Noto Color Emoji font and got Noto Emoji (without Color) font. Gwenview displayed the contour emoji well and in place. No errors appeared, no font cache manipulations were performed before then.

Conclusion

The issue seems to be related to drawing color emojis somewhere deep in Qt. Gwenview is just a convenient tool to test.

This looks even more wrong, as Noto Color Emoji is shipped with KDE Neon, the bleeding-edge Qt, but Noto Emoji is not even in the repos.