Kernel_task is a system process on your Mac that helps manage CPU temperature and performance. If it's using a lot of memory, it usually indicates that your Mac is overheating or that there are resource-intensive applications running.
The graph at the bottom of Activity Monitor shows green memory pressure and you're using zero swap. The machine is fine and not at all memory constrained. You don't have a memory problem.
Is your Mac running warm, or do you have a lot of peripherals attached? Does the CPU tab show an active process using a lot of CPU? Maybe high CPU demand is causing this. Perhaps try closing the Messenger tab in Safari. Facebook (Meta) has a reputation for writing resource intensive code.
Either way, I would not worry about it. Kernel task is an automatic function of the operating system. It's doing a job to protect your Mac.