In the latest snapshot, 21w19a, amethyst geodes are supposed to be rarer. This change actually had the OPPOSITE effect on the geodes. They are super easy to find now! Especially with the C&C data pack (very cool by the way), I already have found a geode in a cave relatively close to the spawn, compared to my 21w11a world, which had a geode very deep underground!
Thank you for your report!
We're tracking this issue in MC-225352, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki