I'm trying to calculate the cost of a job using the usage and list_prices system tables, but I'm encountering some unexpected behavior that I can't explain.

When I run a job using a shared cluster, the sku_name in the usage table is PREMIUM_JOBS_SERVERLESS_COMPUTE_EU_WEST for the specific job_id and job_run_id found in the usage_metadata column. I was expecting to see PREMIUM_ALL_PURPOSE_COMPUTE, or possibly NULL, since both usage_metadata.job_id and usage_metadata.job_run_id are NULL.

Additionally, when I run the job on a Job Compute cluster, I see both the expected PREMIUM_JOBS_COMPUTE SKU and the PREMIUM_JOBS_SERVERLESS_COMPUTE_EU_WEST SKU in the usage records.

Could you please help me understand why the PREMIUM_JOBS_SERVERLESS_COMPUTE_EU_WEST SKU appears in each of these scenarios?