Possible reasons of "Unexpected output from snap-review. snap-review"

I have some snap package building on snapcraft.io. Last few days I see “Unexpected output from snap-review. snap-review” error after snap build. The strange part I didn’t change snapcraft.yaml file for 4 months, but started getting this error only a few days ago.

Any hint how to debug it?

strange thing: build with confinement: strict works well, but confinement: devel doesn’t :thinking: Everything else is identical.