Did you edit and save the excel file in Teams manually?
Does this issue only happened in Excel file?
Based on my knowledge, AutoSave is enabled when a file is stored on OneDrive, OneDrive for Business, or SharePoint Online. It automatically saves your changes to the cloud as you're working. And if other people are working on the same file, AutoSave lets them see your changes in just a matter of seconds. Could you check if it is your situations?
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