When you log in to your online account in the Merchant Portal, you will see your Feed Quality Score. This value indicates the completeness of the columns that are important for Google PLA. Please click on "see feed quality details" (highlighted in yellow).
When scrolling down, you will then get an overview of the individual "Errors" and "Warnings". An offer is only invalidated by an error (i.e. not played), not by a warning.
On the same page, you can find the feed specifications, which contain detailed information about all columns.