Didn't the science officer say something about the failed subjects being volunteers? That doesn't sound like they were clones to me.
Maybe the tanks were occupied by inferior donor
strandcasts with lower "M-counts" than Baby Yoda and were therefore responsible for the failed dark troopers.
Keep in mind: it's now canon that Rey's father was a completely non-Force sensitive (but otherwise normal) strandcast of Palpatine and we're only a few years away from her birth.