>>528672109
>>528672219
>>528672242
>cut content can't be changed
They literally just changed Rot to Poison and changed his textures slightly. Here's why I think this:

1. if you look at the scorpion's model, there are little bubbles over his body that are usually associated with scarlet rot on it. They painted them black, I assume they were originally red.
2. it is confirmed that there is a cut content boss that was supposed to be inside the Grand Cloister' big room.
3. it is confirmed that the avatar of Rot was indeed a "great scorpion"
4. Scorpion Stinger's description (the item that you found at the place he was supposed to be): Dagger fashioned from a great scorpion's tail, glistening with scarlet rot. A ceremonial tool used by heretics, crafted from the relic of a sealed outer god.

I think the Moth was supposed to be the boss but during some point in development they decided to reuse that asset to make a fun duo fight.