
This is the expected behavior since you are adding the App web part for the Announcement list, so it will add the list view with toolbar on the page by default.
See a reference here: News and Announcements web parts in SharePoint.
Currently, there is no such web part that can display the contents of the latest announcement item in SharePoint. All web parts will display the list/items on page and users need to click on them for details.
As a workaround, you can put the contents of the announcement directly with a Content Editor web part with the desired text format.
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