The most common cause of young pepper leaves curling and stunting are thrips or mites. Mites are very tiny insects. Pepper thrips are fairly large but are usually found in a rolled up leaf. Other types of thrips can be very tiny.
Peppers do not take kindly to soaps, so I would use either alcohol sprayed under the leaves or 3 in 1 garden spray that contains sulfur and pyrethrins. Sulfur and pyrethrins is a good combination to get rid of mites which are really tiny spiders.
It is sold as a concentrate or ready to use spray. I take it these plants are indoors. Pyrethrins are good up to 1 day of harvest but can be toxic to animals so make sure you do the spraying in a well ventilated and safe place away from children and pets. Pyrethrins are also toxic to bees so I usually only use this to control mites on plants that are not in bloom and I usually isolate the plants from the healthy plants anyway so the mites don't spread and I can control what gets sprayed on. Sulfur alone will work, but it is hard to find sulfur dust and you have to know how to use it and follow the label instructions.
"Sulfur sprays can be used on some vegetables, fruit trees, and ornamentals. This product will burn cucurÂbits and other plants in some cases. don't use sulfur unless it has been shown to be safe for that plant in your locality. Use liquid products such as sulfur and potash soap combinations (e.g., Safer Brand 3-in-1 Garden Spray) rather than sulfur dusts, which drift easily and can be breathed in. don't use sulfur if temperatures exceed 90Â°F, and don't apply sulfur within 30 days of an oil spray. Sulfur is a skin irritant and eye and respiratory hazard, so always wear appropriate protective clothing."
https://www.saferbrand.com/resource/uplo ... ctions.pdf
Happy gardening in Hawaii. Gardens are where people grow.