Also, do magic items retain their magical properties after leaving the feild? If so, it’s still a pea shooter.

This is a good question. Is the ring a “magic remover” or a “AoE magic suppressor”?

If its a supressor then this is a double edged item. If you’re wearing it on your hand and get healing cast on you, your hand and whatever is near it doesn’t get healed. This would be bad news because the instinct is to grab or hold wounds to stop bleeding. This would mean you can still bleed out of the cleric is pouring every bit of their mana into healing you.