I'm not sure if this happens on offline mode. I've been playing LAN minecraft on the snapshots leading up to 1.16. In every instance (pre7, pre8, rc-1) my diamond efficiency iv pickaxe has a problem where it'll mine sandstone as quickly as internally possible, however the sandstone block will simply disappear and reappear on every hit, like rapidly flicking an on/off switch of some sorts
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However, we are already tracking this issue, and this report is a Duplicate of MC-172550, which is a report that has not been resolved yet.
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