The default value of the proportional line spacing is 6% instead of 100%

[Verhoeckx]

Description:
The default value of the proportional line spacing is 6%, while this should be 100%.

Steps to Reproduce:

1. Open a new document
2. Add some text
3. Select the text
4. Click on the line spacing icon
5. Select Proportional in the drop down menu

Actual Results:
The default value of the proportional line spacing is 6%. When opening the drop down menu, the default value of the proportional line spacing is applied immediately and this makes the text really small.

Expected Results:
The default value of the proportional line spacing should be 100%.

Reproducible: Always
User Profile Reset: Yes

Additional Info:

Version: 25.8.1.1 (X86_64) / LibreOffice Community
Build ID: [54047653041915e595ad4e45cccea684809c77b5](https://git.libreoffice.org/core/commit/54047653041915e595ad4e45cccea684809c77b5)
CPU threads: 8; OS: Linux 6.16; UI render: default; VCL: gtk3
Locale: nl-NL (en_GB.UTF-8); UI: en-GB
Flatpak
Calc: threaded

• System: Fedora 42 Silverblue
• The bug already exists for a few releases.
• The 6% is also shown when the item 'Single' is opened in the line spacing drop down menu (see attachment).

Bugzilla:
I was advised to report this bug here. You can find the related bug report on Bugzilla here:
https://bugs.documentfoundation.org/show_bug.cgi?id=168434