Some third-party Apps have not yet been updated by their Developer to accommodate iPadOS multitasking controls. In this respect, if you have a problem with a specific third-party App when used with iPad, you would be well advised to report the issue to the respective App Developer - as only they can resolve the issue by updating their App:
How to contact an app developer - Apple Support
Be aware that iPadOS 27 refines both multitasking and the positioning of the associated traffic-light controls. The iPad User Guides provides appropriate documentation:
Work with multiple windows at once on iPad (iPadOS 26) - Apple Support
Work with multiple windows at the same time on iPad (iPadOS 27) - Apple Support
If you are having difficulty with multitasking when using specific Apps, consider temporarily selecting Full-Screen Apps mode from iPad settings:
Settings > Multitasking & Gestures > Full Screen Apps
