1. Open Writer
2. Type something and select it
3. Format - Character - Font Effects
4. Input some small value into Transparency
Reported by Leandro in bug 134408
The Transparency field was added in 7.0 and it probably behaved like this from the start - didn't bibisect. I checked with linux-64-7.0 repository.
Version: 220.127.116.11.alpha0+ (x64) / LibreOffice Community
Build ID: 2081eac430ac69619149e44b453a2d7dda41fc83
CPU threads: 2; OS: Windows 10.0 Build 19042; UI render: Skia/Raster; VCL: win
Locale: fi-FI (fi_FI); UI: en-US
Can still be reproduced.
Version: 18.104.22.168 (x64) / LibreOffice Community
Build ID: 85569322deea74ec9134968a29af2df5663baa21
CPU threads: 4; OS: Windows 10.0 Build 19045; UI render: Skia/Raster; VCL: win
Locale: en-GB (en_US); UI: en-US