@Yung-Hang Changโ :
Thank you for bringing this to our attention. It does seem like there could be a potential issue with the way Pandas interacts with DBFS, especially when writing to a mounted ADLS location with a read-only service principal.
We suggest that you file a support ticket with Databricks support team with the details of the issue, along with the notebook screenshot, so that our team can investigate and provide a resolution. You can do this by clicking on the Help icon in the Databricks workspace and selecting "Contact Databricks Support".
In the meantime, you could consider using the methods that correctly throw the permission denied error or using a different storage location with the necessary write permissions until the issue is resolved.