CS:GO font is half-broken, refusing to render special characters like ღ

**Game information**
Counter strike global offensive / CS:GO

**Distribution name and version where applicable**
Arch Linux

**Flatpak info**
```
Flatpak 1.15.4
nvidia-535-54-03
default
host
```

**Problem description**
Simply posting `ღ` in the game chat makes the message empty, not even tofu is displayed.

This works both on Windows and on Steam Native.

Other characters are also broken and break player names, I am using this one as an easy test.

**Does this issue reproduce with native Steam**
No, native steam can render the ღ character correctly.

Reproduce the empty-chat and broken-player-name behavior for the `ღ` character in CS:GO through the Flatpak on Arch Linux, then compare it with native Steam as described. Done means special characters render instead of producing empty messages or broken names.

Written by the indexing model from the issue text.