There are a lot of End Dragons in the end

Thank you for your report!
However, this issue is Invalid.

Your Minecraft version is outdated. We only take issues for the latest release and the latest snapshot.
Please update to the latest version as it includes the newest fixes. If you still have this problem after updating, then please create a new issue.
In case of a game crash, please also attach the crash report found in [minecraft/crash-reports/crash-<DATE>-client.txt|https://minecrafthopper.net/help/finding-minecraft-data-folder/].

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I'm not sure if 1.21 is available.
Because I can't choose 1.20.4):
So I can only choose 1.21.

@unknown What version of Minecraft are you playing on? 1.20.4 or 1.21? 
In your description you wrote "(Minecraft 1.20.4)", that is not the latest version of Minecraft. We only accept reports for the latest release, (now 1.21). 

I can't reproduce this bug just treat it as a joke

Resolving as Cannot Reproduce per the reporter's comment.
By the way, it appears that your game, launcher or server is modified.
We only accept issues that can be reproduced in a vanilla environment.

• Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.

• A world which had previously been opened with a modified client might be corrupted. Please try reproducing the issue in a newly generated world.

• Any plugin issues need to be addressed to the creator of the plugin or resource pack.

• If you have problems on large servers like Hypixel, please contact them first as they run modified server software.

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