(And, if you like, do as TFA says and rephrase the code into your own house style as you’re transcribing it. It’ll be better for it, and you’ll be mentally parsing the code you’re copying at a deeper level.)
I'm amazed that people don't see this. Absolutely nobody would claim that copying a novel is the same thing as writing a novel.
Which: of course you can. Not least because both your coworkers and these coding agents produce changes with explanatory comments on any lines for which the justification or logic is non-obvious; but also because — AI PR or otherwise — the PR consists of commits, and those commits have commit messages further explaining them. And — AI submitter or otherwise — you can interrogate the PR’s submitter in the PR’s associated discussion thread, asking the submitter to justify the decisions made, explain parts you’re suspicious of, etc.
When you think about it, presuming your average FOSS project with an open contribution model, a PR from an AI agent is going to be at least strictly more “knowable” than a “drive-by” PR by an external one-time contributor who doesn’t respond to discussion-thread messages. (And sure, that’s a low bar — but it’s one that the average accepted and merged contribution in many smaller projects doesn’t even clear!)