One thing disappointed me after the clean install of Catalina on the MacBook Pro: while it had regained a lot of drive space, there should have been more. Then I twigged: I’d set the Photos app to hold full rresolution photos after the rebuild, before that I’d chosen to optimise the Mac’s storage of photos, keeping the full res ones on iCloud and lesser ones on the Mac.
Full res pics come down if I edit a photo.
I’m seeing 156 GB of free space, it was 117 GB before the rebuild.