Are coronal loops on the sun an optical illusion?

Me no think so Kimosabe...

Me neither.

I've looked at the pictures and I can't see it as a surface either. A telescope located at either L4 or L5 looking at a different angle would settle the question, I would think.

Coronal loops have been studied for quite a while and are still not well understood.

"Coronal heating problem[edit]

For broader coverage of this topic, see Stellar corona § Coronal heating problem. Unsolved problem in physics:

Why is the Sun's Corona so much hotter than the Sun's surface?

(more unsolved problems in physics)

A closed loop of magnetic field, a flux tube above the solar surface, does not by itself constitute a coronal loop; it must be filled with plasma before it can be called a coronal loop. With this in mind, it becomes clear that coronal loops are a rarity on the solar surface, as the majority of closed-flux structures are empty. This means the mechanism that heats the corona and injects chromospheric plasma into the closed magnetic flux is highly localised.^[7] The mechanism behind plasma filling, dynamic flows and coronal heating remains a mystery. The mechanism(s) must be stable enough to continue to feed the corona with chromospheric plasma and powerful enough to accelerate and therefore heat the plasma from 6000 K to well over 1 MK over the short distance from the chromosphere and transition region to the corona. This is the very reason coronal loops are targeted for intense study. They are anchored to the photosphere, are fed by chromospheric plasma, protrude into the transition region and exist at coronal temperatures after undergoing intensive heating.

The idea that the coronal heating problem is solely down to some coronal heating mechanism is misleading. Firstly, the plasma filling over-dense loops is drained directly from the chromosphere. There is no coronal mechanism known that can compress coronal plasma and feed it into coronal loops at coronal altitudes. Secondly, observations of coronal upflows point to a chromospheric source of plasma. The plasma is therefore chromospheric in origin; there must be consideration of this when looking into coronal heating mechanisms. This is a chromospheric energization and coronal heating phenomenon possibly linked through a common mechanism."

https://en.wikipedia.org/wiki/Coronal_loop

Progress on coronal heating seems to be made:

https://www.cnet.com/science/space/the-suns-puzzling-heating-problem-is-closer-to-being-solved/

https://www.cnet.com/science/space/the-suns-puzzling-heating-problem-is-closer-to-being-solved/

“Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” - Sherlock Homes”

Sherlock missed something. Maybe two things that are impossible explanations because neither accounts for all of the evidence, together can account for all of the evidence.

If we add gravity into the equation, along with the instability of the field under these conditions, then it seems to me the coronal patterns emerge...

The European Space Agency's Solar Orbiter will get an even better perspective on these coronal loops than a telescope at either L4 or L5. The data from this orbiter is new. It will take time to validate and cross-reference with terrestrial observations. I suspect the theoretical papers the OP initially cited were published deliberately prior to the orbiter's data being released so the theory would be "untouched" by observed data.