this gives you some idea of the wide variance of light, especially note the ultraviolet, there is a wide difference between the darker and lighter parts, in general already there is sunspots but the bright areas are also quite varying in intensity around that, the dynamic range of the visible spectrum cameras is low, it would require a proper HDR capture to really see just how much the brightness varies
the UV also gives you some idea of how much the pops and zaps of those plasma filaments is constantly changing, on the Space Weather News channel he always starts the show with images of the sun as it is, animated, and the bright flashes that occur around the edges especially are easy to see how they would make what we see from far away fluctuate randomly
planets don't fluctuate in their bightness so much because they absorb a lot of the light and diffuse the light widely across the surface, so they appear not to flicker in the same way... they also get darker just like the moon, but being further away you just can't see them at all when they are at an angle where the bright side is facing away from you