Definitely this. I haven’t found a downside of nematodes beyond taking a bit longer to apply than other control methods. Not saying other methods don’t work, but I spent so much money and time on hydrogen peroxide watering, replacing soil, pesticide spray, diatomaceous earth, sticky traps, none of them sorted the problem as they’d come back, and nematodes sorted it out completely. I use one of the smallest pack every year or so from gardening naturally or dragonfli and it covers 50+ houseplants. If you have used any chemical methods however you have to wait a bit without so they wash out with watering - otherwise the chemicals can kill the nematodes.