iPadOS14 and iPadOS15 differ in a number of aspects - the implementation of Widgets in the Today view of the first Home Screen differing considerably between the two major versions.
Whilst you are now able to freely position widgets on any of the Home Screens, you have lost the “compact” first Home Screen layout (that previously provided a compressed 5x6 grid of App/Folder icons simultaneously with the Today view.
Now, without the previous compressed view, individual Widgets can be freely placed on any of the Home Screens. Where used, Widgets individually occupy elements of a 4x6 icon grid - with configurable widgets occupying 1x1. 1x2 and 2x2 elements of the grid, displacing App/Folder icons as necessary.
The net effect of adding Widgets to the Home Screen(s) results in reduced efficiency in using available screen space of the Home Screens. You cannot restore the previous compact view with the Today view. You can however, also place Widgets in a Slide Over view that can be summoned from any Home Screen - but this cannot be persistently docked with the first Home Page.
Apple do invite constructive feedback, comments and feature requests via their product feedback pages. For iPad and iPadOS:
Feedback - iPad - Apple
You are encouraged to make use of this facility in expressing any views concerning issues, bugs, or functionality changes of which you are unhappy.