In my opinion, that is completely normal "felt" or "fibers" that some cactus produce. Some produce it from areoles like this plant. It is generally longer/denser on new growth (exactly as in your plant). The theory is that this is temporary shade for the new growth at the plant apex.
If you scrape all the areoles with their felt off, you probably won't kill your plant, but it will look bad and will be scarred forever.
Cochineal will be on the areas between the areoles, not exclusively in the areoles. See image below.
The good news is that you've got new growth which is a positive sign towards it being healthy.