The phone has turned on the accessibility menu function. Click the icon to pop up a quick navigation menu. You can turn this feature off in accessibility settings.
Setting path:
realme UI 7.0 & 6.0：
Settings > Accessibility & convenience > Accessibility > General > Accessibility button
realme UI 5.0 & 4.0：
Settings > Additional settings > Accessibility > General > Turn off the Accessibility button
realme UI 3.0：
Settings > System Settings > Accessibility > Vision > TalkBack > Shortcut > Turn off the Accessibility button.
realme UI 2.0 & 1.0 Setting path：Settings > Additional settings > Accessibility > TalkBack > Shortcut > Turn off the Accessibility button.