SignatureDoesNotMatch after udpate to boto3-1.36.2

[svoop]

My Gentoo box has pulled boto3-1.36.2 and ever since, duplicity throws:

Giving up after 3 attempts. S3UploadFailedError: Failed to upload /tmp/duplicity-xxxxxx_2-tempdir/mktemp-xxxxxxxx-3 to mybox-config-xxxxxxxx/duplicity-inc.20250203T044213Z.to.20250205T181016Z.vol1.difftar.gpg: An error occurred (SignatureDoesNotMatch) when calling the PutObject operation: Invalid argument.

I'm using Google cloud storage (nearline) EU region over S3 with --s3-endpoint-url="https://storage.googleapis.com".

There's a corresponding issue over at boto3, but I don't know how the fixes/workarounds proposed there can be applied in the context of duplicity.

Any hint is very much appreciated!