Most recently: Opus 4.6 screwed up using a common and well documented API (Qt), then when asked to debug the observed issues, blamed "a Qt bug" and wrote a whole layer on top of the API to work around the issue caused by its incorrect use of the API.

It did the above twice in a row around different parts of the API.

The thought that there are almost certainly devs out there merging Claude PRs without the skills or volition to push back on its screwups is not comfortable.