„you should use the ProductPageLoadedEvent as the event, you use will always be fired, if a review is loaded, which means also for API, admin, etc
the PageLoadedEvent is only for the Storefront.
then have a look at the Page objects and the classes which extend from it. Page itself extends from Struct which comes with a addExtension method. with this you could add data for the Storefront“ - From Michael Telgmann