When I spawned in an overworld drake, it was the normal color but upon leaving and re-entering the game it changed its color to red and now all overword drakes spawned are red, including untamed ones. I didn't edit the game at all.

Steps to Reproduce:

1. Go to Creative Mode
2. Spawn an Overworld Drake
3. Leave Minecraft (not just the world)
4. Rejoin the game and load the world

Photo:

That's not a bug, it's the christmas skin for the OWD. All dragons have a christmas skin that appears on it's own. You can disable it in the config

If you want to disable it go to the config folder, open the wyrmroost-client.toml file and change deckTheHalls = true to deckTheHalls = false