macOS behaviour changes?

Decided to try Sequoia on a new external drive on an M1 Mini - I'd been using Monterey.

Installed 15.01 (installer identified as 15.1), then updated to 15.1

I'm pretty sure I disabled Desktop/Document folder syncing soon after installation.

Now my user folder Desktop/Documents folders have gone and it seems to have enabled itself, maybe after the 15.1 update?

I can see this option is now in Finder settings as well as iCloud Settings, don't recall it there in Monterey.

I've never been quite comfortable with this feature, though really should try it.

The problem being I had iCloud documents organized for non-syncing local folders and files are starting to end up where I hadn't planned them to be - will the iCloud folders potentially appear differently now on other Macs not syncing? Appreciate (I think) a 2nd Mac would get separately named iCloud Desktop/Documents folders but what about the situation when you boot from several different drives on a given Mac as I've done for years? Does each separate boot drive have its own iCloud folders or is it tied to the Mac hardware itself?

Decided to try to attach an old scanner to Sequoia and was pleased there seemed to be legacy and newer drivers for it. Downloaded both installers (to local Downloads folder) and quickly realized they were probably identical - what surprised me was that despite downloading sequentially the 2nd download overwrote the first, on earlier macOS versions the 2nd download would have a number appended to the filename or generally with other actions prompt a 'keep both' type dialogue. Is the default now to overwrite identically named files? Can this be changed?

Once the software was installed I scanned 2 documents - the 2nd overwrote the 1st in iCloud Documents as the software didn't update the filename - potentially dangerous had I not noticed and shredded both.