Sticky plant - Anthurium
Hello, I have had this plant for over 6 years. This recent problem has been an issue for maybe 9 months, if I a remembering correctly. I have tried treating with an insecticidal soap twice to no avail. Plant 3 will show you what is on the stems and leaves. Currently, I have 3 red leaves. The newest one is a vibrant red and looks healthy. The older ones are a pail red. Even some of the green leaves have some brown areas but most do not. The floor and furniture around the plant is sticky. I think whatever is on the plants spreads in some way.
Your anthurium has scale, which is a type of insect with a protective covering. We can clearly see many scales, on the mid-vein particularly, in the last photo. Brown soft scale is the most common scale to infest houseplants, but there are many species.
Read through our webpage on scale of houseplants: https://extension.umd.edu/hgic/topics/scale-insects-houseplants
A systemic insecticide is absorbed into the "system" of the plant, and then ingested into the scale when it sucks on the leaf and stems.
Be sure to wipe off all the scale you can before applying any insecticide. Next summer, put your plant outside, if you can, so that beneficial insects outside can kill them.