mintty resets transparency to 100% with first command run

[tps800]

Description / Steps to reproduce the issue

After latest upgrades mintty starts with transparency parameters set to "off". After executing commands transparency ist set to 100%. Going into options, without changing anything, pressing button "apply", then save. Transparency is back to 0% -- until the next command is executed.

$ mintty --version
mintty '3.8.1' 2025-09-18_06:11 (Msys-x86_64)
© 2025 Thomas Wolff, Andy Koppe
License GPLv3+: GNU GPL version 3 or later

$ pacman -Q mintty
mintty 1~3.8.1-1

/etc/minttyrc:
$ cat /etc/minttyrc
Columns=100
Rows=27
Term=xterm-256color

$ cat ~/.minttyrc
Columns=260
Rows=105
Transparency=off
OpaqueWhenFocused=yes
ThemeFile=dracula
Locale=C
Charset=UTF-8
RewrapOnResize=yes
Language=@
StatusLine=no
BackgroundColour=0,94,163

Expected behavior

mintty keeping opaque settings and respecting them, even after executing commands.

Actual behavior

mintty changing to opaque 0% after executing commands until you open configuration and apply it again.

Verification

• I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MINGW64_NT-10.0-17763

Are you willing to submit a PR?

No response

[tps800]

This is only with cmd.exe running with mintty. Other shells (bash, dash, fish, mksh, tcsh, zsh) seem to work as expected.