You have probably used the trick of holding down spacebar to reach the higher blocks of wood that you normally wouldn't be able to reach when chopping down trees. When you do this you constantly jump up and down and for some reason the block breaking doesn't reset even though you can't reach the wood for a short time, allowing you to make progress and break the wood. This also affects me negatively, for example, I broke a piece of obsidian in a farm that converted nether quartz ore to nether quartz, right in front of my eyes, while i was still placing the ores down. I was very surprised when this happened but I think this is the cause. Is this a glitch or not?