Thank you for reporting the bug. I can not reproduce the bug in

Version: 25.2.0.3 (X86_64) / LibreOffice Community
Build ID: e1cf4a87eb02d755bce1a01209907ea5ddc8f069
CPU threads: 16; OS: Windows 11 X86_64 (10.0 build 22631); UI render: Skia/Vulkan; VCL: win
Locale: de-DE (de_DE); UI: de-DE
Calc: threaded

ans also not in 

Version: 25.8.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 1fc03eaed2899ac041f660f54cb1facb71390ccf
CPU threads: 16; OS: Windows 11 X86_64 (build 22631); UI render: Skia/Vulkan; VCL: win
Locale: de-DE (de_DE); UI: de-DE
Calc: threaded

Sorry, I missed the important reproducing procedure.

New reproduction procedure
--------------------------

Steps to Reproduce:

1. Open new Calc.
2. Insert "A" into Cell [A1], and Change the background color to red.
3. Option > LibreOffice > Appeearance > Option Appearance > Light - Check

Actual Results:

4. The font color is black.

Once the Light mode is selected, the original white font color is not restored.
It appears that you need to reset your profile.

Please note that this bug is not seen in Version: 25.8.0.0.

This bug can also be seen in Writer.

(In reply to Jessica from comment #1)

Causes xml include.

<item oor:path="/org.openoffice.Office.UI/ColorScheme/ColorSchemes/org.openoffice.Office.UI:ColorScheme['COLOR_SCHEME_LIBREOFFICE_AUTOMATIC']/FontColor"><prop oor:name="Dark" oor:op="fuse"><value>0</value></prop></item>

<item oor:path="/org.openoffice.Office.UI/ColorScheme/ColorSchemes/org.openoffice.Office.UI:ColorScheme['COLOR_SCHEME_LIBREOFFICE_AUTOMATIC']/FontColor"><prop oor:name="Light" oor:op="fuse"><value>0</value></prop></item>

Once you tamper with the Scheme, it is set to 0 and the automatic text colour remains black unless you manually change it back to -1.

Not Reproduced with

Version: 25.2.0.0.alpha1 (X86_64) / LibreOffice Community
Build ID: e3a80ef423457e6634be97665732b2181c944d4c
CPU threads: 4; OS: Windows 10 X86_64 (10.0 build 19045); UI render: Skia/Vulkan; VCL: win
Locale: ja-JP (ja_JP); UI: ja-JP
Calc: CL threaded


Reproducible with

Version: 25.2.0.1 (X86_64) / LibreOffice Community
Build ID: ddb2a7ea3a8857aae619555f1a8743e430e146c9
CPU threads: 4; OS: Windows 10 X86_64 (10.0 build 19045); UI render: Skia/Vulkan; VCL: win
Locale: ja-JP (ja_JP); UI: ja-JP
Calc: CL threaded

@nobu, please clear your user profile.

Then apply one of the offered Appearance themes and retest.

Believe will find the issue only occurs with the default "Automatic" color shceme in place which draws its colors from os/DE, i.e. the 'System' colors.

A change to Light or Dark will corrupt the default colors.

This is corrected in builds of master against 25.8 but fix could not be added to 25.2 builds.

The only way to clear a munged 'default "Automatic"' color scheme is to reset the user profile.  Recommending users avoid the 'Light' | 'Dark' radio buttons when using the os/DE provided Automatic colors.  Instead just allow os/DE light or dark mode to assert.

Expect this is a dupe of bug 164392 and already corrected for 25.8

(In reply to V Stuart Foote from comment #6)
> @nobu, please clear your user profile.

I have already mentioned in my description that resetting the profile will solve this problem.

And I will also mention that if this bug is only a FontColor issue, it can be fixed by changing the advanced settings from "0" to "-1".

(In reply to V Stuart Foote from comment #7)
> Expect this is a dupe of bug 164392 and already corrected for 25.8

We knew that we would not see any bugs in version 25.8.
I could not find any known bug reports because I do not understand any abbreviations or technical terms and they have already been resolved.
I don't understand the text, but it looks like an identical bug.

*** This bug has been marked as a duplicate of bug 164392 ***