So the way it works on stirling side is we just grab whatever files are in static if their naming and path is the same on stirling pdf side
In this case any files you place will override any files placed in here
https://github.com/Stirling-Tools/Stirling-PDF/tree/main/src/main/resources/static
since you want to override the favicon itself then you would nee dto change favicon.svg for the homepage icons and favicon-16x16.png etc for the favicon itself (smaller sizes for better loading on SSO side)