Reminders used to be all or nothing. Now you set them per calendar, so a match can ping you an hour ahead while a TV premiere stays silent. Set it once and your calendar app follows.
Every synced calendar now carries its own reminder setting. Pick the lead time that suits each one, and Google Calendar or Outlook applies it to the events we send.
Calendars you subscribe to by link also show a short note explaining that reminders there are controlled by your calendar app, not by us.