There is no ‘official’ Intervals app. There are a lot of third party ones, that offer a view of what the Intervals API makes available.
My guess is that you have one of the AI apps making a schedule for you but failing to send it to Intervals.icu. And since Intervals.icu is the one sending it to Garmin, you’re not seeing it on Garmin…
Post a screenshot of what the app looks like, and give us the ‘exact’ name.