Hi Cooney,
Sorry for the inconvenience it may have caused.
Actually, the Excel worksheet you use in Microsoft Teams is the integration of Excel for the web with Microsoft Teams. In this regard, you can log in to SharePoint Online to visit the corresponding group site of this team and open the file in Excel for the web to check the result.
Besides, you can open the Open in Desktop App within Teams to edit the workbook directly in the Excel desktop app. As a lightweight product of Office, Office for the web lacks some advanced features of the Office desktop app.
And may I know if the problem occurs in all worksheets opened with Microsoft Teams? Or just this one? Do you encounter any similar problem when using Word or PowerPoint within Teams?
Best regards,
Madoc