It's sometimes difficult to tell the difference between sunburn, chill injury, and a reaction to contact with a phytotoxic substance. If you haven't exposed your plant to chill considered extreme for a tropical plant, and you haven't moved the plant recently into a spot with much brighter light, it's a good bet that it's from the dishsoap you've been using or the vehicle by which the neem byproduct was delivered. One example of a 'vehicle' would be linseed oil seeing service as a carrier of pigments and other oil-based paint ingredients.

Dishsoap attacks the wax in the plant's cuticle, which reduces the leaf's ability to retain moisture and protect itself from pathogens.

Can you rub the "scale" off easily with a fingernail? If not, they may be a normal part of your plant's morphology.
Ficus often have regularly spaced white dots inside of and along
leaf margins that are often misidentified as pests or glands. They
are lithocysts that contain crystals of calcium carbonate or calcium
oxylate called cystoliths. The dots on your plant look too irregular to be lithocysts, but then, the image might not be showing all you can see by observing with a leaf in hand.

The darkened leaf tissue is not how over-watering, under-watering, or a high level of dissolved solids (salts) in the soil solution presents.

Al

Hello Al: Thank you so much! The “scale” does come off when I rub it and when I’ve washed individual leaves. So with your information, I’m wondering if the culprit is both whatever the scale is and my causing more problems by washing each leaf with the dish soap, water and neem oil concoction I created. I had thought that maybe my homemade recipe was a culprit, that’s when I purchased the spray from Bonide. You’ve just confirmed my intuition. And with your guidance, I’ve looked at the bottle and went to the Bonide website, but there are no other ingredients listed other than the 1% active ingredient of potassium salts of fatty acids (PSFA) so I can’t tell if there is an oil based ingredient. But given that PSFA yields soft soaps and are a component of fat or lipids, I’d imagine this spray is no good either for the Ficus Alii. Do you have a recommendation for a safe treatment of scale? There are some leaves with many white dots and some with just a few, none of the patterns are regular or routine. I’ve found it on an upstairs ficus as well. It’s a large plant, but I’m considering a trip to the shower before I start any new treatments to see if I can clean off whatever damage I’ve done trying to fix the initial problem of bugs... Thank you so much for all of your help! Marcie

I'm thinking the culprit is the dishsoap, and wouldn't be worried about the commercially prepared insecticidal soap. When I use neem oil, I use only pure cold-pressed product, such as that packaged by Dyna-Gro.

Lots of growers use dishsoap in home concoctions, but that doesn't mean it's advisable. Dish soaps and most other household cleaning agents destroy cuticular wax and roots' lipid membranes. In addition, dish soaps have a number of other phytotoxic ingredients in them, so they would best be avoided for use on plants.

I don't mess with scale when I encounter it. The most effective way to be rid of scale is to spray the tree with something like Bayer 3-in-1 Insect, Disease, and Mite control, with imidacloprid. Don't get the 3-part product with fertilizer as one of the parts. You cannot spray indoors. You must be outdoors and it must be warm enough that you can allow the application to dry before bringing it in. If you can't or don't want to do that, you can buy a 1.47% imidacloprid soil drench, and mix it with water at 1-2 tsp/quart/liter. Drench the soil, making sure the entire top of the soil is absorbing water, so as the water moves down through the soil the active ingredient is binding to all soil particles. You could also mix a bucket of solution and allow your plant to soak in it for an hour or so to ensure the entire soil mass is treated.

Drench: https://www.homedepot.com/p/Compare-N-Save-32-oz-Systemic-Tree-and-Shrub-Insect-Drench-75346/203112613?cm_mmc=Shopping%7CG%7CBase%7CD28O%7C28-2_FERTILIZERS%7CNA%7CPLA%7CFixed%7c71700000041079887%7c58700004701920670%7c92700039807472367&gclid=EAIaIQobChMI-K_su_zU4AIVkhh9Ch3S_QUUEAQYBCABEgI9KPD_BwE&gclsrc=aw.ds

Bayer: https://www.lowes.com/pd/BAYER-ADVANCED-3-in-1-Insect-Disease-and-Mite-Control-32-fl-oz-Concentrate-Garden-Insect-Killer/1000180241

Al