The QtWebEngineProcess.exe builds from Qt 5.15.x do not contain FILEVERSON, PRODUCTVERSION. Also the "Qt Company" copyright etc. are missing. In Qt 5.12.9 the information is correctly include in the binary's resources.
This is problematic for MSI based installers which use the version information to decide whether to upgrade files or not.
AFAIK the .rc files are usually created by qmake - I've no idea why this does not work with the 5.15 builds.