Thanks for using the Apple Support Communities. If you are having issues with your shared Bookmarks, Favorites, and Reading List across your devices, you may find the information and troubleshooting steps outlined in the following article helpful (while the article doesn't specifically address Favorites, it uses the same iCloud syncing service as Bookmarks and Reading List, so the troubleshooting should apply there as well):
Get help using iCloud Bookmarks and Reading List - Apple Support
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Question: All my bookmarks, favorites, and my reading list have disappeared on Safari?