DIAGNOSIS The robot's wheel encoders or cliff sensors are dirty. The robot thinks it's slipping or falling, causing erratic steering corrections.
FIX Turn the robot over. Clean the main wheels, pulling out any wound hair. Wipe the four cliff sensors (black plastic windows) on the underside with a dry cloth. Also, clean the front caster wheel and its housing.
IF THAT DIDN'T WORK The problem is high-pile carpet. The robot's software struggles with deep carpet navigation. In the app, set the carpet setting to "Boost" and turn off "Carpet Detect" to force a consistent pattern.
HEADS UP On very dark carpets, the cliff sensors may falsely trigger. Place black electrical tape over the sensors as a last resort; this voids warranty but can fix the issue.