Family Historian Version 7 introduced Sources created from Source Templates, which are underpinned by -specific GEDCOM extensions which will not export readily to other products (such as website generators, GEDCOM tools, or other genealogy products and services)
This is covered in the manual Getting the Most From Family Historian in either Chapter 14 – Merging, Comparing and Splitting Tree Files or in later editions Chapter 15 – Compare, Merge, Split, Copy and Export GEDCOM Files
Many users upload copies of their family tree to web-based genealogy platforms, both for public visibility and convenient searching of the platform’s records