It seems my Peperomia graveolens has rotted. Only one of its shoots, thankfully. :( I'm going to try to salvage it though, since I spotted it before the entire shoot was destroyed. I cut off the top with a sharp knife, and it is now drying. I think the consensus on the internet is to let it dry for a week before replanting it... we'll see how it does...

see where the stem near the root has gotten squishy?

Luckily, the majority of the plant is still ok...