extract-source failing oddly: gbp export-orig yields 'FATAL: invalid argument'

Hello,

festvox-ru has troubles with the extract-source step:

https://salsa.debian.org/tts-team/festvox-ru/-/jobs/1296703

gbp:info: All Orig tarballs 'festvox-ru_0.5+dfsg.orig.tar.bz2' found at '/builds/tts-team/festvox-ru/debian/output'
gbp:info: Creating festvox-ru_0.5+dfsg.orig.tar.bz2 from 'upstream/0.5+dfsg'
gbp:info: Disabling 'cleaner' hook
gbp:info: Exporting 'HEAD' to '/builds/tts-team/festvox-ru/debian/output/festvox-ru-tmp'
gbp:info: Moving '/builds/tts-team/festvox-ru/debian/output/festvox-ru-tmp' to '/builds/tts-team/festvox-ru/debian/output/festvox-ru-0.5+dfsg'
gbp:info: Performing the build
Uploading artifacts for successful job
00:57
Uploading artifacts...
/builds/tts-team/festvox-ru/debian/output/: found 1981 matching files and directories 
WARNING: Uploading artifacts as "archive" to coordinator... failed  id=1296703 responseStatus=502 Bad Gateway status=502 token=8CXYsi5z
WARNING: Retrying...                                context=artifacts-uploader error=invalid argument
WARNING: Uploading artifacts as "archive" to coordinator... failed  id=1296703 responseStatus=502 Bad Gateway status=502 token=8CXYsi5z
WARNING: Retrying...                                context=artifacts-uploader error=invalid argument
WARNING: Uploading artifacts as "archive" to coordinator... failed  id=1296703 responseStatus=502 Bad Gateway status=502 token=8CXYsi5z
FATAL: invalid argument                            
Cleaning up file based variables
00:01
ERROR: Job failed: exit code 1

502 Bad Gateway looks to me like an issue on the infrastructure. Perhaps it is due to something particular in the tarball or such? I however don't really see what.