Simply put, I have custom eventContent renderers for my primary events and I want to add a google calendar feed as a secondary source of events, problem is my custom eventContent renderer (which is not adapted to the gcal events) apply to this source too.

Relevant code:

<FullCalendar
  plugins={[dayGridPlugin, listPlugin, googleCalendarPlugin]}
  ...
  eventSources={[
    events, // 'personal' events with extendedProps
    { googleCalendarId: GOOGLE_FRENCH_HOLIDAYS_CALENDAR, display: 'list-item' },
  ]}
  views={{
    dayGridMonth: renderGridEvent,
    dayGridYear: renderGridEvent,
...

renderGridEvent is a custom renderer which use extentdedProps, etc… from my personal events and thus doesn’t work with the gcal events.