Great question — answering as the UphillTech team:
Structured data operates at the page level. Google's perspective : Relevance Your structured data should be a true representation of the page content. and Location Put the structured data on the page that it describes, unless specified otherwise > by the documentation. Therefore, the link must point to the page the content of which is presented in structured data.
Full answer by user29419: https://webmasters.stackexchange.com/a/136154 (CC BY-SA 4.0).
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