Hey @AnthumChris. Thanks for your question.
We simply report on the transfer size which may or may not be compressed.
We do mention this in the description, although only the Total Kilobytes section includes the link to the W3C page on transfer size:
The sum of transfer size kilobytes of all external stylesheets requested by the page.
Would it be helpful if we link all instances of “transfer size” in the report to make this clearer? We can also be clearer that transfer size is compression-agnostic.
I’d be open to including uncompressed stats in the report if it seems generally useful. Meanwhile those stats could be manually analyzed in BigQuery if you want to get the answers sooner.