With the bonemeal obtained from a skeleton farm, I attempted to grow a bunch of potatoes to trade with a farmer villager. To do this, I held the potatoes in my off-hand slot and the bonemeal in my main hand, so that I could just rapid-fire plant the potatoes, immediately bonemeal them until they were fully grown, harvest them, repeat. This went fine for a few minutes, then the farm block suddenly broke. This repeated every time until I ran out of bonemeal and stopped doing this. When I stopped mid-frenzy with bonemeal still in my hand, the dirt block was partly broken, and stayed that way until I continued instead of resetting. In the attached video, you can tell the block is getting gradually more broken as I continue.

Reproduction: Potatoes in off-hand, bonemeal in main hand. Right click until the potatoes are fully grown, left click to harvest, right click to repeat the cycle until the block breaks. usually happens about halfway through the stack of bonemeal, on average.