Did you also encounter zombie nodes after a launch failure?
Everyone I know who works with ROS 2 encountered the following issue at least once:
You edit a launch file, get an error during startup (misspelled node name, syntax error, ...) and are left with some of the nodes still running in the background because the launch wasn't cleaned up properly. Many people don't notice this and get weird or even dangerous behavior because of this. It is especially frustrating for beginners working with ROS 2.
One might think that this is a limitation of ros launch, but it is actually a bug. There is code present that already tries to clean up in that case. But it has a tiny 3 loc bug, which assumes that a currently idling executor won't have any scheduled work left to do in the near future therefore allowing the parent process to terminate early. A friend of mine submitted the fix over a year ago (https://github.com/ros2/launch/pull/901)
And now my frustration. I understand that maintaining software on the scale of ROS is a hard and exhausting task. But it is also frustrating to spend days tracking down an issue, creating a PR, writing tests for a piece of software as popular as ROS only to get essentially ghosted for a year, while that issue effects people probably daily. There a a few issues like this that every body encounters and with a little attention could really improve the perception of ROS in the community.