It could be thrips. When infested, leaves turn yellowish-brown and deform. Look for small black droppings along the leaf veins, and silvery, shiny spots on the leaves. The insects are usually found under the leaves. Setting up blue sticky traps could help identify them well if they stick to them; adult thrips are attracted to the blue color.
Thrips are 1 - 3 mm in size with a narrow, elongated body, often yellowish, brownish, sometimes black. Mostly found under the leaves. The larvae are usually yellowish and smaller, found under the leaves or on the leaf veins.
Take your time and carefully check the affected areas.
If it turns out to be thrips, take the pot, place it in a plastic bag, and carefully seal it at the bottom around the plant’s stem. Then, gently rinse the leaves in the shower. The bag will prevent your soil from getting wet. Afterward, place a dome over the plants to increase humidity, which they don’t like.
If the plant is too small to shower, you can use predatory mites or lacewing larvae to combat the thrips.
If the infestation is not yet too far advanced, you can mix olive oil or neem oil with pH-neutral soft soap and water and spray the leaves from above and below. To do this, mix two tablespoons of olive oil with a squirt of soap in 1 liter of water, or one teaspoon of neem oil with one teaspoon of soap and 1 liter of water. Repeat this process every 3 days until all thrips and eggs are dead.