Block breaking

Probably relates to MC-271406

Could you please attach a video showing the issue?

Are you running it on a server or on a low-end computer? If so, this may be a lag issue.

Kelianor, from what I can see of MC - 271406 I can assume that it is the same thing

and Viradex, It's a singleplayer world and I've never had a problem before

We do not have enough information to find the cause of this issue.

Please record a video of this happening and attach it to this report.
If you are on Windows, you can use Windows+Alt+R to open a built-in app for recording game footage.
If you are on Mac (Mojave or later), you can use Shift+Command+5 to open a built-in app for recording your screen.
In case you don't have a program to record videos, we recommend using the free recording software OBS.
In case the resulting video file is too large to be uploaded to the bug tracker directly, please upload it elsewhere (e.g. as unlisted video on YouTube) and link to it here.

_{This issue is being temporarily resolved as Awaiting Response. Once the requested information has been delivered, the report will be reopened automatically.}

Quick Links:
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this is the video:

This kind of blocks reappearing is caused by severe server-side lag.

While the lag occurs, please press F3 + L once, then wait a short moment until profiling has finished.
Afterwards, please attach the generated .zip file containing the profiling results here. The file path is shown in chat; the file can be found in [minecraft/debug/profiling/<DATE>.zip|https://minecrafthopper.net/help/finding-minecraft-data-folder/].

If you are playing on a server please additionally run the command /perf start to create a profiling report for the server. In case you do not have the permission to run this command, make sure that you're a server operator.
Once profiling has finished, please attach the generated .zip file from debug/profiling/<DATE>.zip of the server folder.

_{This issue is being temporarily resolved as Awaiting Response. Once the requested information has been delivered, the report will be reopened automatically.}

Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki

How is it caused by server lag if I'm not on a server?

In singleplayer, the game starts a server locally that only you can join. Server lag is different from client (FPS) lag in that you still have a smooth visual experience but the game reacts delayed, e.g. it takes a while for blocks to drop items, or the game to register that you've broken a block.

Regardless, please attach the profiling report I asked for so that we can look into this.

I did a command (not cheating command) and it seemed to have stopped the lag. I don't think it was a bug, sorry for the false bug