Missing "mainContent" or "excerpt" from Json

Site URL: https://www.streetartflekkefjord.no/gatekunst/terje-andersen?format=json-pretty

Hi I'm making a PWA and I'd like to fetch some Json content from this webpage https://www.streetartflekkefjord.no/gatekunst/terje-andersen?format=json-pretty  as you can see the Json file is there but there's not "content", normally on other webpages made with squarespace I can find the  content on the Json file within "mainContent" but not on this particular one, can anybody tell me what's missing, is there any anything I can do to make it appear or has anybody experienced the same thing? (I have access to the backbone "editor" so if there's any setting that needs to be changed I can try it)

In advance thanks

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