Fast Data Transfer costs not making sense

My Fast Data Transfer metrics don’t match up with what Chrome Devtools is showing. I even looked at the raw http request/responses using Fiddler… the amount of data transfer I’m being billed for is much larger than what these tools are showing. I’m on pro plan and tried all the observability/usage tools, I can’t really get a granular look at where the data is coming from. Anyone else have similar issues / can point to best next steps?