Interesting.
Do the Chinese characters still show up correctly in the Inventory System Editor?
Are you using TextMeshPro to display the text? Does the text at run time, in the TextMeshPro Text component Inspector look garbled too?
Perhaps the issue isn't with the inventory system but with TextMeshPro:
I can display Chinese characters fine using the default skin. But as soon as I try to skin them, using my own fonts, I can't get them to display (in the editor). The fonts are imported using the Unicode setting, but fonts that support Chinese characters (as confirmed in tests in other programs)...
answers.unity.com
Let me know if that's not the case