winver)Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes
Problem description:
We can use Stylus.IsPressAndHoldEnabled="False" to hide the touch feedback when we enable touch feedback in Windows 10.
It can work well when we do not enable the WM_Pointer message.
How to enable touch feedback in Windows 10? See 3 Ways to Enable or Disable Touch Feedback in Windows 10
Actual behavior:
We can find the touch feedback when we enable WM_Pointer message.

Expected behavior:
The behavior of the WPF application is the same as before enable the WM_Pointer message.
We can use Stylus.IsPressAndHoldEnabled="False" to hide the touch feedback. When we hold the screen, the gray rectangle is not displayed.
Minimal repro:
https://github.com/lindexi/lindexi_gd/tree/41884562/KemjawyecawDurbahelal
Maybe the possible reason is that the code in HwndStylusInputProvider is not entered
The WPF will use the HwndPointerInputProvider when we enable the Pointer message. The main code is in System.Windows.Interop.HwndSource.Initialize
if (StylusLogic.IsStylusAndTouchSupportEnabled)
{
// Choose between Wisp and Pointer stacks
if (StylusLogic.IsPointerStackEnabled)
{
_stylus = new SecurityCriticalDataClass<IStylusInputProvider>(new HwndPointerInputProvider(this));
}
else
{
_stylus = new SecurityCriticalDataClass<IStylusInputProvider>(new HwndStylusInputProvider(this));
}
}
But the HwndPointerInputProvider ignore the Stylus.IsPressAndHoldEnabledProperty
But when I listen to the message and execute the same logic as HwndStylusInputProvider, nothing happens.
This is my demo code: https://github.com/lindexi/lindexi_gd/tree/81b2a63a/KemjawyecawDurbahelal
I think my code is correct, because when I do not enable the WM_Pointer message, this code can work well.
Most helpful comment
But when I listen to the message and execute the same logic as HwndStylusInputProvider, nothing happens.
This is my demo code: https://github.com/lindexi/lindexi_gd/tree/81b2a63a/KemjawyecawDurbahelal
I think my code is correct, because when I do not enable the WM_Pointer message, this code can work well.