What do brown spots on a fiddle leaf fig mean?

Not dying, but it is telling you something specific, and where the spots sit tells you which thing. Fiddle leaf figs produce two quite different brown spots that need opposite responses, so read the pattern before you change anything.

Reading the spots

Dark brown or nearly black patches starting in the middle of a leaf, often with a yellow halo, usually mean too much water and the beginnings of root trouble. Dry, tan, papery browning that starts at the edges and works inward usually means the opposite: the plant is drying out, sitting in a draught, or getting scorched by direct sun through glass. Lower leaves only, dropping cleanly, is often just the plant shedding as it grows taller.

How to fix it

1. Check the roots before anything else. Tip the plant out and look. Firm, pale roots mean the trouble is environmental. Brown, soft, sour-smelling roots mean overwatering, and it needs fresh dry mix now.
2. Fix light and airflow, one at a time. Bright indirect light, away from radiators and cold draughts. Change one variable so you can tell what actually worked.
3. Then leave it alone. These plants hate being shuffled around. Constant relocation causes more leaf drop than any of the above.

What to expect

Spotted leaves never heal, so do not measure progress by them. Success is new growth coming in clean, which usually takes four to eight weeks in the growing season.