Hey @Josh Chan 123, thank you for the clear repro steps and screenshots, that makes this so much easier to look into!
You're right that this isn't how it's supposed to work. I gave your steps a try on my end and was able to reproduce it too. Here's a quick screen recording showing the same thing happening. A section title should carry over in full when you export or copy it as an image, so having the Chinese characters drop out and only "Testing" show up in the PNG isn't expected. I've gone ahead and flagged this to our team so they can dig into it.
One thing that'll help narrow this down: does the same thing happen if the section title is only in Chinese (no Latin letters mixed in), and are you seeing this in the browser, the desktop app, or both? That'll help point our team in the right direction.
In the meantime, here's more on Export your FigJam board if it's useful. Really appreciate you taking the time to report this so thoroughly!