It isn’t just the 4 new Unions from Kaiba’s Structure Deck that got updated. Three other Unions in the Deck got errata’d as well.

Y-Dragon Head

Z-Metal Tank

Heavy Mech Support Platform

All are confirmed to have the following text changes:

Previously, their texts specified that a monster could only be equipped with 1 Union monster at a time. This is now omitted from their current texts.

Previously when unequipping, they could only Special Summon themselves in Attack Position. They can now Special Summon themselves in Attack Position or Defense Position.

Previously, their effects applied while equipped to a monster would only work if equipped by their own effects. They now apply their bonuses and can be Special Summon if equipped by monsters like Relinquished.

For Y and Z: Previously, they only destroyed themselves when their equipped monster would be destroyed by battle. They now destroy themselves when their equipped monster would be destroyed by battle or card effect.

For Heavy Mech Support Platform: Previously, it only destroyed itself when its equipped monster would be destroyed (no specific method). It now destroys itself when its equipped monster would be destroyed by battle or by card effect.

There’s no confirmation at this time that the OCG plans to update other Union monsters with this new series of texts, merely that the three reprinted Unions and the four new Unions share this text.

Rulings concerning these altered Unions will be later posted on the YGOrg site over the weekend.