When using efficency to mine blocks, they dont break, they stutter, become "ghosts" but come back after, only comes into affect when insta mining, so efficency 3 or above with sand or efficency 5 and haste 2 for stone as two examples.
Link to video showcasing the bug.
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BugTracker
BugTracker
In that case this is being tracked in MC-271406, thanks for taking you're time on making this report 🙂
migrated
Does MC-271406 describe you're issue?