Content copy tool in Aem as a cloud

Hi All

As I noted  from adobe document, Content copy tool in AEM as cloud , the limitations are ,

The content copy tool has the following limitations.

Content cannot be copied from a lower environment to a higher environment.
Content can only be copied from and to authoring services.
Cross-program content copy is not possible.
Running concurrent content copy operations on the same environment is not possible.
Up to 50 paths can be specified per content set. There is no limitation on excluded paths.
Do not use the content copy tool as a cloning or mirroring tool because it cannot track moved or deleted content on the source.
The content copy tool has no versioning capability and cannot automatically detect modified content or created content on the source environment in a content set since the last content copy operation.
If you want to update your destination environment with content changes only, since the last content copy operation, you must create a content set. Then, specify the paths on the source instance where changes were made since the last content copy operation.
Version information is not included in a content copy.

My Query Is,

What is the maximum amount of content that can be transferred from a higher environment to a lower environment at one time?

We were unable to find this information in any Adobe documentation. If the content transfer fails, we also cannot determine the reason for the failure.

Could someone please share any information on this if available?

Thanks