I was placing and breaking a torch over a dirt block, awaiting for grass to spread on it, and found that the dirt block started displaying break marks, which grew every time a torch was placed and broken, until it looped back to the block being normal again.

In the meantime, grass actually spread to the block, and the breaking marks remained. However, when I reached the final level of break marks and placed and removed another torch, the grass block was destroyed and dropped as a normal dirt block, as if it was broken by hand.

I only tried once, but the marks didn't seem to appear when breaking the torch with the HUD off (after pressing F1), though it worked when I turned it back on.

This was tried in a multiplayer vanilla server.

Update 26/03/20: I tried again to replicate the bug and was successful. New information, when I actually hit the block, the breaking marks reset. Dirt indeed just loops back, while grass blocks are broken. I tried it over dirt and grass blocks in the wild, so it's not affected by surrounding blocks. I also tried it over stone brick blocks, and was successful, however the breaking marks appear much more slowly (presumably because it takes much longer to break them by hand, it's actually much faster when using a pickaxe). The tool being used affects the speed with which the marks appear, and stone brick blocks do indeed break and drop if the torch is broken with a pickaxe.