Before 1.6 I would've said to go to the shrine of illusions to change your pet's breed, but unfortunately that was removed with the ability to have multiple pets. As far as I can tell, you have two options.
1. Adopt a new cat from Marnie and remove the old one using
butterfly powder from Krobus. I would not recommend this, though you seem to be at a point in the game where none of the below issues would be completely prohibitive.
Pros:
- No save file editing if you're uncomfortable with it.
- Even if you're ok with editing your save, moving the file to a computer and changing things on a different device can be a hassle.
Cons:
- Costs
60,000 to do.
- Requires the sewer key to remove the pet
- Requires having max friendship with the existing cat to adopt a new one
- That friendship will all be lost starting with a new pet
- This one may only be me, but you'd just know that the new pet is not the same one you started with
2. Send your save file to a computer and edit your save. I don't normally lean towards editing saves to do things that could eventually be achieved in game, but spontaneously shapeshifting cats are not something that can easily be accounted for. I found
this guide on reddit for editing your pet which seems to still be accurate. (The numerical value for the grey cat is 1, and the value for the yellow is 2, so if the number appearing under pet breed is 1, then your problem may be purely visual, in which case I don't think I can help you.)
Pros:
- Doesn't cost you any time or money in game
- Keeps everything else about your pet the same.
- Can be done no matter where you're at in terms of progression.
Cons:
- Requires your save file to be transferred from your phone to a computer and then back.
- Save file editing is not always the most reliable thing, there is a reason nearly every guide on save editing says to make a backup of your file.
