Uploading firmware from CI ends in HTTP Status 502

MNT (mntre.com) recently started automatically uploading Firmware from CI to the embargo remote. As part of the CI job, firmware for two devices is built and uploaded one after the other.

Every so often the upload of the second firmware fails with HTTP Status 502.

Example pipeline log: https://source.mnt.re/reform/pocket-reform/-/jobs/13386

Our upload-fw.sh script is here: https://source.mnt.re/reform/pocket-reform/-/blob/main/upload-fw.sh?ref_type=heads