I've run into a number of bugs in Jupyter labs. I'm surprised that a system as mature as Jupyter labs would still have such bugs. Here are two that I remember.
2. Often when I paste into a code or markdown block, the item I paste is duplicated. It doesn't happen all the time, but it does happen often enough to be annoying. One way to generate the error (at least for me) is to copy a URL from my browser and paste it into a markdown block. Here's an example.