Is there a way to get your erased data Apple Watch back
Is there a way to get a Apple Watch back once u erased the data
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It backups with the iPhone backup.
If you have a backup of your iPhone from before you erased it you can try to restore your iPhone from that then restore the apple watch.
Back up your Apple Watch - Apple Support
How to back up your iPhone, iPad, and iPod touch - Apple Support
The backup must be before you erased the watch, if not there is no way.
Data that is stored in icloud will appear on the apple watch regardless if you can restore it from a backup or not.
Good luck!