poetry update --without=dev changes dev dependency versions in lockfile

[LincolnPuzey]

I have a project with main and dev dependencies.
I want to run poetry update --without=dev to update all my main dependencies, but not those in the dev group.

When I run this command, only the main ones have a new version installed, but both main and dev dependencies are changed to a new version in poetry.lock.
This leads to the dev dependencies getting updated later unintentionally (e.g. when running poetry sync).

I would expect this command to not change the version of dev dependencies in the lock file. Given the --without option is documented as

--without=WITHOUT      The dependency groups to ignore. (multiple values allowed)

Is this a bug? or an oversight of the documentation?