Hello @Lukasz Opasiak - Thanks for reaching out.
That doc explains the fields that are available from cost analysis, UsageDetails API, and scheduled exports.
And we are not clear exactly whether you're talking about cost analysis downloads, invoice usage downloads, or scheduled exports.
If you are referring to Cost Analysis , then see below :
Cost analysis doesn't support all fields and generally works by grouping and aggregating data. When data is aggregated, we won't show all fields. If they want all fields, they need to use Exports or the UsageDetails API.
For instance, when we group by resource group, we can't show the resource details because that would result in more rows than there are resource groups. There are also cases where we don't have resource groups (like a reservation purchase) and this is when people end up with a null or empty string value for the resource group name.
Hope this helps.
If the above response helped, please feel free to "Accept as Answer" so it can be beneficial to the community.