Xiaomi
Enable or Disable Google Assistant via the Home Button auf Xiaomi
On Xiaomi phones running MIUI, a long press on the virtual home button is wired to Google Assistant by default. This shortcut lives under the button configuration, not inside the Assistant app itself, which is why disabling it from within Google Assistant never works.
The setting controls what happens specifically on a press-and-hold gesture. A regular tap still takes you home, so turning the shortcut off will not affect normal navigation.
To change it, open Settings ➔ Additional settings ➔ Button shortcuts ➔ Launch Google Assistant, then Choose an option.
From there you can switch the action to none, keep Google Assistant, or in some MIUI versions assign a different app or gesture to the long press. Any change applies immediately, no restart needed.
If Google Assistant still opens after switching the option off, check that no other gesture (like a swipe from the corner) is also mapped to it, since some MIUI builds allow more than one trigger for the same action.