
Maybe one of the succulents that’s lower in look like an echeveria that’s beginning to etoliate, therefore creating a stem in the center/“growing up” Whatever it is, if the succulent is stretching, it needs more light. Succulents need a lot more light than you think and light in homes is often a lot darker than it seems. I keep mine outside during the summer (when temps are consistently >50° F) in the shade to prevent burning, but they get direct evening light
Your plant is still fine and healthy, it’s just reaching for sun. If you’d like to remove the stem for aesthetic purposes, you can cut it, allow it to callous over (the stem tip will dry out), and then you can put in in soil and it can propagate from there into a new plant. Otherwise, your plant is healthy, she just wants more light. I’d recommend a gradual transition into brighter light (don’t just throw it in immediately because it may burn, allow it to adjust)