Click on the Date table
Under Table Tools Tab > Click on Mark as Date Table dropdown > Select Mark as Date Table
Set the Date Column to Date
The Date column should now look like this:
Power BI creates its own date table for each date found in your dataset. This can bloat the size of your file. Best practice is to switch this off.
Go to File tab> Click on Options and settings > Click on Options
Select Data Load tab in CURRENT FILE section, uncheck Auto Date/Time