This bug is very complicated, but in short, I will list what it does. This glitch makes you in a boat server-side, but not client-side. Its side effects include but are certainly not limited to, the ability to make ghost blocks on certain servers, the ability to place blocks behind yourself while in a boat, the ability to float in mid-air, and the ability to increase your attack range by a few blocks.
As the videos showcasing the bug were too big for file limit, I uploaded them on youtube as unlisted videos
1. Join a multiplayer Minecraft server on the affected versions
2. Craft and place a boat on the ground
3. Rapidly right-click (you might need an auto clicker)
4. You are now in a boat server-side, but not client-side
MC-205477 Occasional desync when trying to enter/exit a boat while the server is lagging