Unforge deals damage only to the creature that the Equipment was attached to when the Equipment was destroyed. It doesn’t deal damage to creatures that the Equipment had previously equipped.

Unforge : règles, fonctionnement et interactions (MTG)

Unforge is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Destroy target Equipment. If that Equipment was attached to a creature, Unforge deals 2 damage to that creature.

How it works : Unforge

Original English text — Wizards of the Coast / Scryfall

#1December 1, 2004· Wizards of the Coast
Unforge deals damage only to the creature that the Equipment was attached to when the Equipment was destroyed. It doesn’t deal damage to creatures that the Equipment had previously equipped.
No other card is named in this ruling.