Where I explored old caves, the chucks was missing and there is holes all over where the cave system was.

Is this only happening on a Bedrock Dedicated Server? What plaform are you using?
This ticket will automatically reopen when you reply.

I am using Minecraft windows 10 edition

Thank you for your report!
We're tracking this issue in MCPE-98789, so this ticket is being resolved and linked as a duplicate.

If you have a copy of the world available, please attach it to the main ticket. If the world is larger than 10MB, you can upload it to OneDrive or a similar file-sharing site, and then share the link.

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 – 📖 BDS Wiki – 📖 FAQs