In build 1201, Blue Wizzrobes, Mirror Wizzrobes, Fire Wizzrobes, and any other Wizzrobe that moves like the classic Blue Wizzrobe experience knockback from attacks. In past versions they did not. I suspect it is a result of the updated enemy editor.
To easily demonstrate the problem, use the mirror shield against them. Because of the knockback, they can't get close enough to require the player to move. It makes Mirror Wizzrobes far easier than normal.
On the other hand, Wizzrobes did have knockback in the gameboy games, so this behavior is true to them. Perhaps an option to enable/disable knockback for wizzrobes could be added to the enemy editor?