(which makes sense, as I think one motivation for reasoning traces is to explore different options and approaches. So it makes sense that there is a lot "but wait, let me reconsider" in them)
What I found surprising is how strongly "logical contradictions" seem to influence the thinking trace. E.g. I had a situation where I accidentally copied a python file into a repo, but forgot to add a package that the file was depending on. Then I (somewhat carelessly) commited the file without ever testing it and gave the agent a task to work on the file.
If I had run it in Python, I'd have gotten an "cannot resolve import" error and that would have been the end of it.
Instead, the model went absolutely haywire.
The thinking traces were full of utter confusion how the file could possibly resolve its dependencies - but at the same time, entertaining the possibility that a committed file may have an error was apparently Verboten. Hence, the model wrote up ever more outlandish theories how the file could resolve that package and in the end started to make tool calls outside the repo to explore the entire file system before I stopped it.
Moral of the story: Underspecified requests are fine, but beware of anything self contradictory, it can easily send the Qwen model spiraling.