Unlike iPadOS14 and earlier versions, multi-tasking cannot now be disabled from settings. Multi-tasking has received a significant overhaul, both simplifying its use and introducing new controls.
Key to accessing (or avoiding) and controlling multi-tasking is the small “three-dot” button that is found at the top-centre edge of the screen.
More information about using multi-tasking can be found in this support page:
Use multitasking on your iPad - Apple Support
The iPad User Guide is also a rich source of information about using iPad and its many features. 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
Being a user-to-user technical forum, contributors here have no influence over Apple’s product or feature development. Other than the site Moderation Team, Apple neither monitor nor participate within these support communities.
Apple do invite submission of constructive comments and feature requests via its Product Feedback portal. For iPad and iPadOS:
Product Feedback - Apple