Syncing problem with Microsoft 365 shared calendars in native iOS App

I found a procedure to add shared Microsoft 365 calendars to the native calendar app (iOS).

In the first step, download the official Microsoft Outlook from the appstore and sign in to your MS account. Then click on add shared calendar in the app. Add as many calendars as you want and then let the app sync.

In the second step, go into the native calendar app on your iPhone, click on calendars and swipe down to do a refresh. You should see your shared calendars.

You can then delete Outlook. This works for me, but it may work elsewhere. The sync condition is of course the same MS account on the iPhone and then Outlook