iPadOS multitasking has received a significant makeover from that to which you may be accustomed in iPadOS 18.x and earlier - and may take a little time to learn and adjust your workflows. You would be well advised to review the official iPadOS User Guide and the many available online tutorials (such as YouTube) to become better acquainted with the new multitasking interface and associated gestures and controls:
Multitask on iPad with iPadOS 26 - Apple Support
Work with multiple windows at once on iPad - Apple Support
OS - iPadOS 26 - Apple
Slide Over and Split Views remain - although are accessed differently. You can have two or three App windows side-by-side - or a split the screen into four quadrants.
To access the windowing controls, assuming that the current App window is not maximised; touch-and-hold the traffic-light icon at top-left of the App window to expose the Fill & Arrange options:

A simple tap of the traffic-light button will expand the window control:
- Tap the red button to close the App and associated App window
- Tap the yellow button to minimise the App, but keep the App running
- Tap the green button to maximise the current App window
If an App is already maximised to full-screen, the traffic-light control won't be visible at top-left. A downward swipe from the top-edge of screen will expose the new top-menu bar - and with it, the traffic-light multitasking control button:
