I’m seeing the same issue as @lucyllewy. All builds of the chromium snap now fail on launchpad:
Failed to reuse files from previous run: The 'pull' step of 'launcher' is out of date:
The source has changed on disk.
To continue, clean that part's 'pull' step by running `snapcraft clean launcher -s pull`.
Build failed
See e.g. https://code.launchpad.net/~chromium-team/+snap/chromium-snap-dev/+build/329874.
This is the corresponding snapcraft.yaml. It hasn’t changed significantly since the last successful build (only bumped the version number, which is what triggered the new failed builds), so it looks like this might be a snapcraft regression.