Loki ingester pods fail to flush to S3 storage with "x-amz-content-sha256 must be UNSIGNED-PAYLOAD" error after upgrade to Logging 6.4.6 in RHOCP 4

Issue

• Loki ingester pods fail to flush data chunks to S3-compatible object storage after upgrading Red Hat OpenShift Logging and Loki Operator to version v6.4.6.
• The LokiIngesterFlushFailureRateCritical alert is firing in the OpenShift console.

• Loki ingester logs contain the following error message:

  level=error ts=2026-07-02T06:39:52.189509452Z caller=flush.go:262 component=ingester loop=30 org_id=infrastructure msg="failed to flush" retries=5 err="failed to flush chunks: store put chunk: operation error S3: PutObject, https response error StatusCode: 400, RequestID: , HostID: , api error InvalidArgument: x-amz-content-sha256 must be UNSIGNED-PAYLOAD, STREAMING-AWS4-HMAC-SHA256-PAYLOAD or a valid sha256 value."
  

• Loki Compactor fails to put the objects with the error message:

  2026-07-02T07:06:05.701053175Z level=error ts=2026-07-02T07:06:05.627605124Z caller=delete_requests_db_boltdb.go:94 msg="failed to upload delete requests file" err="operation error S3: PutObject, https response error StatusCode: 400, RequestID: , HostID: , api error InvalidArgument: x-amz-content-sha256 must be UNSIGNED-PAYLOAD, STREAMING-AWS4-HMAC-SHA256-PAYLOAD or a valid sha256 value."