Disabling this feature should be a straightforward process, but sometimes it gets complicated as many OEMs include this feature into the phone. Also, do not underestimate the nuisance the Google Assistant app can create with voice dictation.
Turn Off Google Voice Typing for the Phone
Turn Off Google Voice Typing for the Gboard Application
If Gboard or any other keyboard application has enabled Google Voice Typing in its preferences, then disabling it in the phone’s settings may not stop the Google Voice Typing. Turning it off in the Gboard (or any other keyboard application) may do the trick for the user.
Turn Off Hey Google or OK Google in the Google Assistant Settings
If the Google Assistant is enabled on your phone, it can also be used to perform different tasks including typing. Hopefully, that will end your quest with Google Voice Typing for now. If none of the above do the trick, then check if resetting, disabling/re-enabling, or uninstalling any of the Gboard, Google Assistant/Google Assistant Go, or Google/Google Go apps turns off Google Voice Typing.
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