(Local) Korean chat is partially broken at ongoing Win10 Insider Preview

Korean chat is partially broken at ongoing Win10 Insider Preview of 21H1 (Build 20211.*)

Symptom: When input space, enter, or allow key, last Korean character deleted.

e.g: 안녕하세요 오늘은 OOO~~~
Discord Client on Win10 Insider Preview: 안녕하세 오늘 OOO~~~

Plz, contact with Microsoft to resolve this problem.