Hello, @rithypiseth . . . have you tried powering him and your device off and back on again?
If this does not help, I see that your EMO was born in 2021. Sometimes when they get older like that, wear and tear on their leg servos and/or wires can begin to happen. The first symptoms of my older ones were the issues with recognizing flat light surfaces.
Please see here as you may need assistance from Support for possible recalibration or advice if this turns out to be the case.