So callled "Invincible End Crystals"(They are the end crystals that get spawned in the "animation" when respawning the Ender Dragon) have issues with their hitboxes and teleporting. Everything from creation to the bug is shown in this video: https://youtu.be/WcnbBK3mASA .
Linked issues
Comments

Thank you for your report!
We're tracking this issue in MC-44654, 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
-- I am a bot. This action was performed automatically! Please report any issues on Discord or Reddit