Non-blocking could cover everything from “wow this is kind of jank, but it’s good enough for now and let’s figure out how we fix it later” through to very minor thing like “you have a typo”.
If we blocked on everything being perfect, we’d never get anything finished. Plus, PR’s are free.
Writing a non-blocking review feels a bit like writing to /dev/null. Good to get it out of my system but not much else.
If it's important enough to be tracked then I'd want to make sure that it's been filed properly. It's too easy to forget about such a trivial task, especially in a time crunch.
I trust that it will get done. It is not important to me, whether it happens before the PR goes in or afterwards.
non blocking may be resolved if you have a strong argument for why you did it that way (most people don't, so it ends up being a code change as well).