I had this issue when I used kubernetes, sata SSDs cant keep up, not sure what Evo 980 is and what it is rated for but I would suggest shutting down all container IO and do a benchmark using fio.

my current setup is using proxmox, rusts configured in raid5 on a NAS, jellyfin container.

all jf container transcoding and cache is dumped on a wd750 nvme, while all media are store on the NAS (max. BW is 150MBps)

you can monitor the IO using IOstat once you’ve done a benchmark.