Your character walks away while you hold the Joy-Con still, or the menu scrolls on its own. That is Joy-Con drift: the stick thinks it is being pushed to one side. It is typical of a classic stick: the contact that measures the position wears with heavy use. In a Switch Lite, such a stick is inside the console itself.
FIXNOW replaces the stick in a Joy-Con or Joy-Con 2, in a Switch Pro Controller and in a Switch Lite. A diagnosis comes first, and you know the price before we begin. You can come by in Antwerp or Wolvertem, or ship the device yourself with track & trace.