filename appending extension's last letter is duplicated in Hangul

[SageSage7]

Description of the Issue

the end of the non English filename is duplicated at the end of the extension

Steps to Reproduce the Issue

1. Ctrl+N make a new file and write something
2. Ctrl+S 한글파일이름확장자버그{enter} // with checked append extension {enter} is actual key

Expected Behavior

we expect
한글파일이름확장자버그.txt

Actual Behavior

it makes
한글파일이름확장자버그.txt그

the end '그' of the non English filename is duplicated at the end of the extension
this only occures in non english blocked state
block means combination state like in Korean Hangul which needs combination keystokes to make an one letter.
if you press arrow keys rectangle block state disappear and bug doesn't happen, but this is not natural way.

Debug Information

Notepad++ v8.4.5 (64-bit)
Build time : Sep 3 2022 - 04:05:32
Path : C:\util\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
Cloud Config : OFF
OS Name : Windows 7 Ultimate (64-bit)
OS Build : 7601.24533
Current ANSI codepage : 949
Plugins :
ComparePlugin (2.0.2)
DSpellCheck (1.4.24)
mimeTools (2.8)
NppConverter (4.4)
NppExport (0.4)

[SageSage7]

this bug has happened since several months ago. i mean 8.4.5 is not the beginning version of this bug.