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Why can a red giant be hidden by dust before it becomes a planetary nebula?

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Planetary nebula Southern Ring Nebula as captured by the James Webb Space Telescope in the near-infrared (left) and the mid-infrared (right). The dimmer star at the center of this scene has been sending out rings of gas and dust for thousands of years in all directions. The Southern Ring Nebula is approximately 2,500 light-years away.

Before a red giant evolves into a planetary nebula, it undergoes a phase of rapid mass loss, shedding material through a relatively slow-moving stellar wind.1

During this stage, the star can become heavily obscured by dust that forms from heavy elements present within this outflowing wind. This dust is significant because it is highly opaque to stellar radiation, effectively absorbing light and obscuring the star from view. The grains that constitute this dust are composed of materials such as silicates and carbonaceous components, which condense in the relatively high-density environment of the star's outer atmosphere before being pushed outward by radiation pressure.12

As the star continues to lose its overlying atmosphere, its hot core is eventually exposed, causing the star to become hotter and its radiation to ionize the surrounding gas, which marks the transition into the planetary nebula stage.1