Created attachment 151510 [details] example As title,it is not the file's problem. If I create a new markdown page by Kate and enter Chinese,I can also get a preview with garbled code. The attachment is an example. Windows 11 22.04.1 from Microsoft Store
Could you try if the latest build here https://binary-factory.kde.org/view/Windows%2064-bit/job/Kate_Nightly_win64/ Fixes it? You can just use the ZIP and execute Kate from it after extraction without installation.
This should be fixed in the latest nightlies.