Liquids have enzymes or bleach. They might have oxiclean instead of bleach but apparently the two best cleaning agents don’t exist in liquid together very well.
I always break a corner off the pod and crumble it into the pre-wash partition since watching the video nerdponx in the sibling thread posted (found it through a different post maybe a half year or so ago also here on HN). I also do the hot-water priming when I remember to.
Powder is better. Pods are just powder.