@Inusui
I'm so sorry - I know this is a thousand months too late but I just noticed your poor succulent post from January! It looks like a classic case of rot from either watering too often or from a soil and/or container that holds too much moisture. Unfortunately, most succulents are sold with improper soil or containers. They need gritty soil (at least 50% rocky substrate) and a container with a drainage hole, and only to be watered when the soil is fully dried out. (For me, that's about once every 2 weeks.)

Basically, when moisture sits around a succulent's roots for too long, it weakens the tissues, which opens up a gateway for common soil pathogens to enter. In the wild, succulents live in well-draining sandy soils and on rocky slopes in shallow grit-filled crevices. They're not built for the dark, peat-rich potting soil we use for most plants!

I know it's probably too late for your beb at this point, but I hope this helps you understand what probably happened!