The Bug
While breaking a block and pressing the Escape key to open up the pause menu, then clicking Save and Quit and reopening the world, it will still show the block's mining progress. However, this seems to be a visual glitch, as breaking the block once logged in again seems to restart the mining progress without restarting the actual visual block breaking. Additionally, breaking and replacing the block does not erase the breaking progress. However, after interacting with the block for a bit, the visual effect will disappear. See the video attached for more details.
Note that this bug has no effect on gameplay. The mining progress is most likely a visual glitch.
How to Reproduce
See the attached video for a visual step-by-step example.
Break a block that takes a while to mine such as stone in singleplayer Survival mode.
While holding down the mining button, press the Escape key so that you do not reset your progress while pressing the key.
Save and quit the world, and then reopen it.
Note how the block still has the mining progress. If you try to break it, you will notice how it restarts the mining progress, but not the visual from when you left the world. Also, breaking and replacing the block will sometimes leave the mining progress.
Additional Notes
Related to:
MC-73786 (Static breaking cracks using specific tools and consumables)
MC-54587 (Block breaking progress can be retained by using the world border)
MC-255057 (Client/server desync when breaking block from continueDestroyBlock)
MC-19676 (Breaking particles, sounds, and block cracks can be created in adventure mode)
MC-8472 (Block cracks remain on blocks in adventure mode when losing focus of them)
MC-69865 (Block breaking is not canceled when losing focus of a block)
MC-157404 (Placing/breaking instant-breaking blocks slowly breaks block behind them)
MC-205451 (Breaking block texture remains after breaking item frame/painting)
Linked issues
Attachments
Comments


It's most likely not the same issue @unknown:
Attempting to mine the block again resets the visual glitch for the painting/item frame glitch of MC-205451. This is not the case in my ticket. However, both have the same issue where insta-mining the block and placing it back keeps the visual glitch.
The reproduction steps are pretty different from each other in my opinion, though both are rendering problems.
MC-205451 relates to this ticket but is probably not a duplicate. Please correct me if I am wrong, or if this is a duplicate of another issue. 🙂
Edit: I don't mean for this to be interpreted as a snarky comment.

@unknown then in that case this relates to MC-205451 and I can indeed confirm.

Okay, I'll add this to the 'related to' list. Thanks!

MC-173876 perhaps?

@unknown Yes

👍
Seems to duplicate MC-205451 (the only difference between the two reports are the reproduction steps) but if that's not the case I can indeed confirm.