I get annoyed with "drive-by PRs" only when they lack context or are clearly just a way to get some commits into a project (typos and so on), but any findings that can improve my code or its performance is welcome, in my projects at least.
Sometimes you just don't have the time to get a PR to a projects mergeable standards, but the solution as a reference can have a ton of value for those that eventually get a PR across the finish line.
I would say, though, that agentic coding seriously complicates the entire situation...
Since code is cheap now, why not replace reviewing with reimplementing!