From the PHB rules on opportunity attacks:
You can avoid provoking an opportunity attack by taking the Disengage action. You also don’t provoke an opportunity attack when you Teleport or when someone or something moves you without using your Movement, action, or reaction. For example, you don’t provoke an opportunity attack if an explosion hurls you out of a foe’s reach or if gravity causes you to fall past an enemy.
So if something else moves an opponent (e.g. a Levitation spell), they do not trigger any Opportunity attacks during that movement.
You appear to have taken "even involuntary movement by an opponent can trigger an Opportunity Attack" as a given - this is not the case.