textInputCurrentInputModeDidChange not working when we tap dictation button on system keyboard

I am working on healthcare application which need to show alert for HIPAA compliance when user start using the dictation via system keyboard because textInputCurrentInputModeDidChange not working anymore. @apple could you please suggest us the alternate way or to provide option to disable dictation on system keyboard.

textInputCurrentInputModeDidChange not working when we tap dictation button on system keyboard
 
 
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