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 and controlling (or avoiding) multi-tasking is the small “three-dot” button that is found at the top-centre edge of the visible App windows.
When using Safari, this multitasking button is very close to the URL/Address bar; combined with a likely “conditioned habit” of tapping the centre of the Safari Address Bar, this is a common trigger of unexpected split or slide-over windows.
Be aware that text shown in the URL/Address field is centre-justified; you can tap anywhere in this field to edit the website address. If you follow the usual usage pattern, you likely have a “conditioned habit” of tapping the centre of the field. Instead of tapping the centre of the URL/Address bar, try to consciously tap either side of centre; in so doing, you can completely avoid accidental activation of the “three dot” multitasking button.
Over a short period of time, you will subconsciously develop a new conditioned habit when using Safari - and will hopefully avoid the common cause of accidental triggering of multitasking views.
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
