Hello
To disable text suggestions when using the onscreen keyboard in Windows 11, you can follow these steps:
Press the Windows + I keyboard shortcut to open the Settings app.
Click on the Time & language tab.
Navigate to the Typing section.
Click on the toggle button next to the Show text suggestions when typing on the physical keyboard option.
Please note that this will disable text suggestions for both physical and onscreen keyboards. If you only want to disable it for the onscreen keyboard, currently, there might not be a direct option available in Windows 11.