With the recent update which reverted all paper rebalanced cards, 4 cards were banned in Alchemy: Cori-Steel Cutter, Leyline of Resonance, Monstrous Rage & Sewer-veillance Cam, but 3 other cards which were also rebalanced for being too good: Vivi Ornitier, Heartfire Hero, and Kona, Rescue Beastie weren't banned, and are now legal in Alchemy in their original form.
We have no indication from Wizards that these cards should be legal when the others were banned, and it makes no sense to make Vivi Ornitier legal with Sewer-veillance Cam banned as Sewer-veillance Cam was only hit initially due to its interaction with rebalanced Vivi which no longer exists, so my assumption is that these 3 cards were missed in error similar to Teferi, Time Raveler which was banned in error in Historic Bo3 in the same update.
If these cards were intended to be legal it would be nice to get some clarification, but if they weren't it would be great to get fixed as I feel it could upset the balance of the Alchemy format for its remaining months otherwise.