Ancient city doesn't fully covered with deep dark biome

when located the ancient city. the ancient city is not completely covered by the deep dark biome. this makes a lot of mobs spawn in the ancient city and is very annoying.

There is some seed with this bug :
• 2814761879323725871
• -106006368705497521

Steps to reproduce:
1. Make a new world
2. Locate an ancient city
3. Teleport to ancient city

Observed results:
Some part of ancient city didn't covered with deep dark biome

Expected results:
Ancient city fully covered by deep dark biome