What kind of pest?

The plant gradually fades, the leaves are sticky, just like the window next to which it stands becomes sticky. How to deal with this scourge? Tar soap and alcohol give only temporary results.

Most likely it is a scale insect. It is when it attacks the plant that the leaves become sticky. To get rid of it, you can try treating plants with systemic insecticides, for example: Aktara or Confidor.

Thanks for the advice, I’ll definitely try the remedies you suggested. If I understand correctly, then it would be advisable to replant such a plant, but in my opinion these parasites are sitting inside it.

If the flower is sticky, then the reason may be aphids. If in doubt, you can use a complex insecticide. It is important to thoroughly wash the window and iron the curtains, as insects can lay larvae there.

And I have the same problem (whatever I haven’t done before, I’ll try this again

It’s difficult to tell who has settled there, just by the stickiness of the sheets. Tear off a leaf and take it to a flower shop. There, experts will tell you exactly what to do and how to treat it. Laundry soap doesn't help me for long either.