Some chunks are bugging, even if you did nothing what could lag. It looks like chunks are getting brighter. Mobs on all of those chunks are extremely bugged. If you step on bugged chunk, you can go out only in Spectator game mode. Seen also on 21w08a.
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Chandler
Thank you for your report!
We're tracking this issue in MC-214808, 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.
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