Certain GB18030‑2022 Extension Characters Render Incorrectly in Account Avatar

[micahgodbolt]

Area

React Components (@fluentui/react-components)

Describe the feature that you would like added

Summary
When using account names that contain specific GB18030‑2022 extension characters, those characters render incorrectly (blank or shown as ?) in the account avatar/name picture, even though they render correctly elsewhere in the UI.
The issue affects characters from EXT B–F, GFZB‑196, BX, GX, CX, HX, and IX ranges.

Environment

OS: Windows 11 (24H2, build 26100.4061)
Browser: Microsoft Edge 137.0.3296.62
Language: zh‑CN

Steps to Reproduce

https://stackblitz.com/edit/tav7urwm?file=src%2fexample.tsx

Actual Result

The following characters do not render correctly in the account avatar:

EXT B–F
GFZB‑196
BX, GX, CX, HX, IX

Affected characters appear as blank or ?.
Example affected characters:

GFZB‑196: 𬸚
EXT B: 𢃾
EXT C: 𪜀, 𫜴
EXT D: 𫟰
EXT E: 𬺠
EXT F: 𮓇
BX: 𪛝
GX: 𰉖
CX: 𫜶
HX: 𱘍
IX: 𮯰

Expected Result

All valid GB18030‑2022 characters should render correctly in the account avatar, consistent with their rendering elsewhere in the UI.
Other GB characters and standard ASCII/English characters already display correctly.

Notes

This appears to be a font, glyph fallback, or text‑to‑image rendering issue specific to the avatar/name picture pipeline rather than general text rendering.
The issue is reproducible with valid GB18030‑2022 encoded input and does not affect non‑extension GB characters.