poetry export is implemented by poetry-plugin-export, not by Poetry itself. From Poetry 2.0 (January 2025) that plugin is no longer bundled with a default installation, so the command is missing and Poetry suggests installing the plugin. Add it with poetry self add poetry-plugin-export.
This matters for deployment pipelines built on the pattern of exporting to a requirements file and then installing with pip into a slim image, since the export step disappears when the build agent upgrades Poetry.
Two details are worth keeping. The export includes hashes by default, so the resulting file needs every dependency present and works with pip install --require-hashes; --without-hashes turns that off. And export writes only what the lock resolves for the requested groups, so pass --only main or --without dev explicitly rather than assuming the default matches your install command. An alternative that avoids the plugin entirely is installing directly with poetry install --only main inside the image.