The changelog for 21w19a says:

• Made geodes significantly rarer

However, geodes appear to spawn in exactly the same places and the same frequency as in 21w18a.

Steps to reproduce

1. Generate a world in 21w18a and one in 21w19a, with the same seed.
2. Go into spectator mode and look for geodes underground in 21w18a.
3. Copy your location with F3+C and teleport to that location in 21w19a.
4. Notice that every time, the geode is there in both versions.