Hi there! My partner and I purchased a fiddle leaf fig about 3 weeks ago and we've noticed some dimples/indentations on the edges of the leaves. They seem to be getting progressively larger and it's causing the leaves to curl/dimple further. I can wipe most of the brown 'dust' film off with a wet cloth, but curious as to what's causing the dimples/indentations (and worried it will get worse).

The florist we purchased it from recommended watering once per 3-4 weeks, which we've done once since purchasing. Is this potentially a fungal or bacterial issue? Maybe sunburn?

It's situated in its original pot next to an east facing window with plenty of indirect lighting. It gets some direct sun every morning from 1030-1130am.