Disk Usage 100% with system as the major issue

Lately my laptop slowed down even though I only opened file explorer. I checked my task manager and my disk usage was 100%. I’ve tried many ways that I found on the internet like checking disk C, update windows 10, stopping sysmain, disabling diagtrack, defrag, MSI, prefetch, etc. Still it didn’t work. I checked the details of disk usage and it showed antimalware service executable on top of the list (at the time I ran full scan with windows defender security). When i checked the detail, System appeared to be the major usage factor. Can you help me what’s wrong with this and how can I fix this? Is it possible because of malware?