https://phys.org/news/2018-10-nasa-aqua-satellite-tracks-super.html

In satellite imagery on Oct. 26, the eye had become cloud-filled. Infrared satellite imagery revealed cooler cloud tops (indicating the uplift of air had strengthened) and a contracting eye occurring after the storm experienced an eyewall replacement cycle.

Mature, intense tropical cyclones can and often undergo an eyewall replacement cycle. That's where a new eyewall or ring of thunderstorms within the outer rain bands forms further out from the storm's center, outside of the original eye wall. That ring of thunderstorms then begins to choke off the original eye wall, starving it of moisture and momentum. Eventually, if the cycle is completed, the original eye wall of thunderstorms dissipates and the new outer eye wall of thunderstorms contracts and replace the old eye wall. The storm's intensity can fluctuate over this period, initially weakening as the inner eye wall dies before again strengthening as the outer eye wall contracts.