What I expected to happen was...:

My new world to generate using all 1.19 rules

What actually happened was...:

My new world generated several chunks directly around spawn using 1.17 algorithm for surface biomes, but all underground biomes and biomes past approx -300 are generating as 1.18/1.19 algorithm biomes. (I'm assuming 1.19, but 1.18 & 1.19 look pretty similar in the general vicinity.)

Steps to Reproduce:
1. All I did was start a new world on our existing Java Realm using seed # 606045115702081861, survival mode, easy difficulty. 🤷‍♀️ I can't really re-do it or my kids would mutiny because we've already done a ton of work on our starter base.

2. When I created a single player world using the same seed and settings it worked right.

(Edited to clarify- 1.17 vs 1.19 algorithms, so the bug is in WHERE the biomes appear, not just WHICH biomes appear.)