Why does App Store Connect require a build number higher than previous version's build number for a new editable version with no builds?

Question

I'm using fastlane to upload a TestFlight(upload_to_testflight action) build for version 1.0.10. In my lane, I update the marketing version using agvtool new-marketing-version and then use increment_build_number to set the build number based on the latest TestFlight build. Since there are no builds uploaded for the new editable version (1.0.10), I expected the build number to be set to 1. However, I receive the following error:

"The provided entity includes an attribute with a value that has already been used. The bundle version must be higher than the previously uploaded version: ‘37’."

Interestingly, when I upload via Xcode with build number 1, it works fine. Why does App Store Connect enforce that the build number must be higher than 37 (from a previous version, 1.0.9), even though 1.0.10 is a new editable version with no builds? Any insights or documentation on this behavior would be greatly appreciated.