What is the funding fee for Phemex?

Could you please clarify what the funding fee entails for trading on Phemex? I'm interested in understanding the specifics of how it's calculated and what factors influence its rate. Is it a percentage of the trade volume, or is it based on other metrics? Additionally, is the funding fee a one-time charge or is it applied periodically? I'd appreciate it if you could provide a detailed explanation to help me better understand the costs associated with trading on this platform.