What is the status of your synced files? You could recognize status through OneDrive icons.
Please follow this article to know more about OneDrive icons.
If your synced files are downloaded to local and have been deleted, they will show in the local recycle bin.
If your synced files are online and have been deleted, they will show in the OneDrive recycle bin not SharePoint site recycle bin.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.