Hi many thanks for the prompt info & making the team aware!
just to confirm that with spectral layers totally gone, the project file is still the same size, so from my example above if i now
remove spectral layers from source audio track
remove the source audio track
render the bounced stems to new files
cleanup & remove trash in the audio pool
“backup” and minimize files… the .cpr still remains 317mb
and just to confirm there is no 3rd party plugins involved… its only a test project, but im so glad i hadn’t used this on a real project (without a backup)