how come my New Xbox series erased my 360 data?

Thank you for contact us! I'm Anderson, an Independent Consultant and a Microsoft user like you.

good afternoon

if your Xbox 360 account was linked to a Microsoft account, your data is saved in the cloud.

I advise that if you transferred the data directly from another xbox, remove the profile, clear the cache and download the profile directly from the cloud.

Did you manually sync your 360 save data to the cloud?

There's saved data there it says 8.8 mb of saved data. I erase it to try to resync and after i try to resync my saves it comes back but wont sync all i get is new game.

Sorry for the newb question: isn't saved game data backed up to the cloud or is that something I'd have done in settings?

Also, this won't erase my eternal drive too will it?

Well, In my case all games for one and series S/X are safe automatically in cloud, the games for Xbox 360 and classic, I don’t know if they're safe in cloud too or only in drive.

All your information in drive will be erased, games, local saves(have a copy in cloud) and settings.

My guess is that when you connected it to the PC it messed with the 360 file format. The drive will have to be reformatted to work on the 360. The downside is that the data will probably be erased.