Opponent Cast Toph First Metal bender, Toph has ability "nontoken artifacts are lands in addition to their other types (they don't gain the ability to tap for mana)."

I cast witness protection, which states "enchant creature, enchanted creature loses all abilities and is a green and white Citizen creature with power and toughness 1/1 named legitimate businessperson"

I expected Toph's nontoken artifacts to leave the land area and lose the land card type since Toph lost the ability noted above. The loss of ability was even notated in game with it being grayed out, but the artifacts remained in the land area and kept the land card type. When opponent cast even more artifacts, those also were notated as land card types as well. They were notated in blue showing that they were modified to be that way and the only card that could do that was Toph.