Incorrect sprite rendering in "Flash Toukou Matter"

[FioraAeterna]

Describe the bug

If you click through the first few lines of character interaction, you will start to see incorrect sprite rendering like this:

Expected behavior

It should look like this, which it does in original Adobe Flash:

Content Location

https://exapico.freetzi.com/TOUKOUMATTER/yume.html

Affected platform

Browser plugin

Operating system

Mac OS Sonoma 14.7

Browser

Mozilla Firefox 137

Additional information

No response

[torokati44]

Looks like for the faces to appear normal, they have to be mirrored.
And they are, initially:

But then, they lose this inverted World Matrix for some reason: