The Player takes damage after holding space and jumping down one block, one heart gets taken away, to be exact.
To reproduce:
Load up a survival world in 1.21.4 Pre-Release 2
Find a place where you can jump down from a one block height
Jump down while holding space
Linked issues
Comments 2
Thank you for your report!
We're tracking this issue in MC-278518, 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 (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
Duplicate of MC-278518