stumbled on this comment on an OSS issue.

I thought it was an interesting example of how relatively middle-of-the-road comments can actually be pretty negative to receive - and how they can be improved!

"...this doesn't seem to be fixed in the 6.0.0 version"

stated as fact; no acknowledgment that bug could be specific to user/env./use-case

explicitly acknowledge the bounds of your experience:

"Having upgraded to 6.0.0., I am still seeing this error in my app."

doesn't provide an (ideally hosted) example of bug

providing examples means maintainers don't:
1. have to take time to replicate your setup
2. make (potentially critical!) assumptions about your use-case!

"See this fiddle for an example of the bug still present in 6.0.0"

"...please check..."

offloads responsibility for bug/patch verification to maintainer
a hostedexample significantly reduces maintainer's workload - all they have to do is verify our work!

"...and release a new version?"

presumes - both to know the correct action AND to make explicit demands of maintainers' time
trust that people know how to do their jobs and can draw correct conclusions from provided information.

"."

zero positive sentiment or appreciation expressed
show some appreciation

"Thanks for all your hard work on this project. I really rely on it and I'm glad it's so robust!"