When the published desktop is launched, the on-screen keyboard from the client machine appears when clicking on the Start menu or when any keyboard input is needed.
Add the below registry key for disabling the pop-up then reboot the machine –
Location: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\MobileReceiver.
Name: DisableKeyboardPopup
Type: Reg_Dword
Value: 1
Refer below documentation for more details -
https://docs.citrix.com/en-us/citrix-workspace-app-for-windows/configure.html#on-screen-keyboard-control
On some devices and in some circumstances, Citrix Workspace app cannot accurately detect the mode of the device, and the on-screen keyboard may appear when not needed.