Vault and ominous vault can open from every side of block

I don't think this is a bug, and even if it is, its not a huge issue.

Thank you for your report!
After consideration, the issue is being closed as Working as Intended.

Please note, that mechanics of the game may change between updates.
Things such as graphics, sounds, world creation, biomes, redstone, villagers, and animals may not work the same in current versions.

Full Version History – Snapshot Version History – Feature Requests and Suggestions

Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki