This issue was first discovered by Mumbo Jumbo in his Honey block testing video:
https://www.youtube.com/watch?v=SLqwJ2tmYNE
I noticed this and tried it out for myself. I noticed that if you try to push or spawn a Shulker onto a block it will teleport away. It also may teleport the Shulker inside of the block for a brief second, causing a lag spike.
Thank you for your report!
We're actually already tracking this issue in MC-110067, so I resolved and linked this ticket 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 in the future to see if the issue has already been reported.
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