Compare old leaves with the center
An isolated older leaf gradually drying can occur during normal growth. A whole rosette becoming translucent or collapsing in damp medium is a different pattern. Identify the plant and inspect its growing center and base before drawing a conclusion.
Remove fully dead material when it comes away without damaging healthy tissue. Keep a brief record if changes are unclear. Avoid repeatedly repotting or watering a stable plant simply to keep every old leaf permanently plump.
FAQ
Can one dry leaf prove root rot?
No. Diagnosis needs the wider pattern, root conditions and changes over time.
Source
RHS: Growing houseplant cacti and succulents
Related plant reading
Succulent Growing Conditions: Identity Before Climate Claims