Notepad3 (x64) 6.26.227.1 beta

This is a condensed sample for a larger document.

Reproduction steps:
Enable the [Settings2] DevDebugMode=1 in Notepad3.ini. (Optional)
Save the following text to a file with Chinese GB18030. 寄生少女ゆうちゃん
Reopen the file with Notepad3.
Incorrect encoding and content. UCD='EUC-JP' Conf=95% (reliable (90%)) [Invalid UTF-8] - OS-CP='ANSI(CP-936) in the title bar.

This sometimes happens for files that contain something similar, but not always, depending on the content. e.g. the file with following text are correctly identified: 图书 寄生少女ゆうちゃん. But once you remove the "图" or "书" character, the error occurs.

EmEditor always does the correct and identifies the file as GB2312.
Any ideas to change?