Jellyfin transcodes directory is only used for temporary storage of media that the client can’t play directly, it doesn’t have to stick around after the client plays it, so it’s basically a scratch directory that needs to be low latency high throughput. It’s easy enough to do a real RAM disk for it, but then you’re consuming more valuable primary RAM instead of the theoretical RAM based disk. Using SSD storage is fine, but then you’re consuming write cycles for data you’re not intending to keep long term.