Sometimes a cleanup can be skipped between stages, even squashing can't take all optimizations because we need to save the stage/files at the end. But we can just tell to the first stage to not clean the fs and to the following stage that the filesystem is intact. This has the same effect as squashing but can be more generally applied.

  FROM debian:12.10 AS first-stage
  UNPACK debian:12.10
  SAVE STAGE /kaniko/stages/0
- CLEAN

  FROM first-stage AS third-stage
- UNPACK /kaniko/stages/0
  RUN touch test
  SAVE FILES [test] /kaniko/deps/2
  CLEAN

  FROM first-stage AS fifth-stage
  UNPACK /kaniko/stages/0
  COPY --from=third-stage test test