SPFx webpart in MSTeams Desktop Client throws an UnauthorizedAccessException

This question is very similar to a question which has been asked previously on StackOverflow. However, the error I'm getting is different.

AadHttpClient fails when loading SP page with SPFx webpart in MSTeams Desktop Client

I also have a Sharepoint Online site in which I have an SPfx web part that makes use of AadHttpClient. This web part works if I navigate to the Sharepoint site from a browser or open MS Teams web client.

My setup is as follows:

• I have a team in MS Teams
• I added a new tab in Teams and selected Sharepoint from available apps
• I selected an existing Sharepoint site to be displayed

When I debugged the MS Teams desktop client, I have this call in in the Network requests tab:

{"odata.error":{"code":"-2147024891, System.UnauthorizedAccessException","message":{"lang":"en-US","value":"Access denied. You do not have permission to perform this action or access this resource."}}}

I wonder why this only happens in MS Teams desktop client and not on either the web client on Sharepoint Online.

Cross posted from: https://stackoverflow.com/questions/59860729/spfx-webpart-in-msteams-desktop-client-throws-an-unauthorizedaccessexception