Checkpoint pages/sec performance counter constantly zero

First of all, I don't have enough reputation to comment on this post to ask my question, hence asking here. I have a SQL Server 2022 instance which is target of an ETL process, receiving multiple million records every 2 hours. There are also heavy calculations on the same instance resulting in heavy table truncate and writes right after ETL. I have heavy disk writes when ETL starts (Disk Write Bytes/sec performance counter from SQLServer:Resource Pool Stats), but Checkpoint pages/sec is constantly zero at the same time. Recovery interval is set to zero (automatic). How can I find why checkpoint pages/sec is zero? Other performance counters (e.g. Buffer cache hit ratio and PLE) return reasonable values.