Created attachment 189306 [details]
file with color theme using themeOverride
Open attached file in LibreOffice and in PowerPoint. Notice the different colors. The reason is, that the color theme which is used in PowerPoint is defined in a themeOverride element. And such is ignored by LibreOffice.
The file was originally produced by SoftMaker. To be sure, that is has a structure corresponding to Microsoft Office, I have resaved it with PowerPoint 365.
Created attachment 189325 [details]
The example file in PP 2016 and Impress master
Version: 188.8.131.52.alpha0+ (X86_64) / LibreOffice Community
Build ID: 33ae7c12bbdf19b76ced472ca8aed6cf66477bbe
CPU threads: 15; OS: Windows 10.0 Build 19045; UI render: Skia/Raster; VCL: win
Locale: en-US (hu_HU); UI: en-US