During the update to iPadOS15, some Widgets were installed on your first Home Screen to illustrate new functionality.
iPadOS15 now allows you to freely position widgets on any of the Home Screens - these Widgets being additional to any that may be installed in the slide-out Today view.
Widgets placed on a Home Screen now individually occupy one or more elements of a 4x6 icon grid. Home Screens without Widgets retain the familiar 5x6 icon grid. The slide-over Today View, previously seen in Portrait screen orientation from the first Home Screen, is still present - and is now also seen in Landscape. However, slide-over does not incorporate the Time and Time panel.
More information about the new Widgets can be found here:
Use widgets on your iPad - Apple Support
Widgets can be simply removed from your Home Screens. Just long-touch on an empty area of a Home Screen until the icons (and Widgets) “jiggle”. While the icons are jiggling, just tap the tiny “x” badge of the icon/widget that you wish to delete. When you’re done, just tap any empty area of the screen.
The iPad User Guide is a rich source of information about your iPad and iPadOS - and is especially useful in becoming familiar with the many changes and new features introduced in iPadOS15. The Guide is available both online using a web browser (such as Safari), or as an Apple Books download:
iPad User Guide - Apple Support
https://books.apple.com/book/id1567104892
