Attachments in Planner
Currently when you upload an outlook file into your files and then attach it to a Planner card the link will not take you to the file - it gives you an error. I have had this problem at two different companies with MS Teams.
Camilo Lopez commented
The error is reproduced with any file because Planner points to the non-existant directory "Shared%20Documents" in Teams SharePoint site.
The file is actually uploaded to the directory "Documents" in the Teams SharePoint site