Yes, although "observation" is perhaps a bit loose. More on that at the end.

For around fifty years, relativists have been interested in how general relativity drives the structure of rings and discs of matter where the inner edges are exposed to general relativity. The motivations are to better anticipate observations that may test general relativity, to understand how to distinguish relativitistic orbits from Newton-Kepler orbits in various ways, and to try to expand our weak understanding of why there are many disc-like structures around ordinary stars (protoplanetary nebulae and so on) and why there are so many discoid galaxies like typical spirals.

The very broad question, decoupled from any theory of gravitation, is: given an initial random ball of matter around a central mass, what drives the ball into a disc?

How this works for accretion structures around a spinning black hole has been the stuff of research for decades, and a 1975 paper (by Bardeen & Petterson) spawned a direction of research from which "today's" particular paper descends: "frame dragging" can evolve a fluid disc surrounding a black hole from a non-equatorial plane into an equatorial plane. ("Today's paper" adds some complications to this decades-old idea by using computers to study the fluid dynamics and magnetics within a somewhat more realistic disc than could be considered decades ago. Additionally, this remains an area of ongoing research and "today's" authors are not the only active group).

I notice I used "scare quotes" above in three ways; the first is simply shorthand for the paper discussed at the northwestern press-release linked at the top of the page. The second is quoting your use of the word observation, and I'll return to that. The third is because "drag" in "frame dragging" gives me itches because it is so hard to understand non-mathematically. Bear with me, I'll spend the next couple of paragraphs on that, scratching my own itch. (Also it turns out I'll use "" in a fourth way, namely surrounding search terms that may be useful for anyone interested in finding out more).

Although circular orbits around a spinning black hole are stationary (they are not accelerated or decelerated by the black hole spin; but for a constant radius from the black hole they may be longer or shorter) the orbits may be deformed in direction orthogonal to the direction of the orbit.

That is, an orbiting body (in free-fall on a circular geodesic) may, without feeling any accelerations or body forces, find itself on an orbit which is in a different plane, or is at a different radius, or which takes a different amount of proper (as in wristwatch) time for a full orbit, or some combination of these.

The effect is called "frame dragging", but again, nothing is really feeling a drag like in a viscous medium (like running into or along with a strong wind, for example). Einstein gets the blame for the use of "drag" since he wrote a letter to Mach in 1913 talking about the plane of an idealized Foucault's pendulum being dragged about by (an idealized) Earth's rotation. Lense and Thirring (1918-1921) were interested in the vanishing of Coriolis forces in certain frames of reference. Cohen (1965) generalized that to the finding of inertial frames of reference within and near rotating masses. These papers all discussed a freely-falling observer feeling no forces (especially not "fictitious forces") who by looking well outside the frame (e.g. at distant "fixed stars") tell that the observer's orbit was influenced by the rotation of the black hole, even if the black hole left no local imprint on experiments. The free-falling laboratory locally inertial frame of reference of the observer was said to be "dragged" with respect to those fixed stars, like Foucault's pendulum's plane.

"Drag" is unfortunate because the presence of these special frames of reference are a feature of the (curved) spacetime under study; they trace out orbits, and one can set up a body so that it follows one of these orbits. The orbits are a special set among a (larger) infinity of possible orbits, but oddly such special orbits seem more popular with matter in an accretion disc. Why? Because the matter is "dragged" there like one would drag a toy truck by its string or iron filings with a bar magnet? No, the matter feels no pushes or pulls, only its orbit changes, and spatially only in directions orthogonal to the orbital direction.

Today's paper introduces pushes and pulls within the matter of the accretion disc. The matter feels those (scatterings, collisions), even in the directions along the orbit itself. This results in observable structure when matter is deposited randomly around a black hole (rather than placed very very carefully into an equatorial orbit).
Those structures easily remove energy from matter in the disc, allowing that matter to fall onto closer orbits (and ultimately into a plunging orbit into the black hole itself).

If they exist, those structures should be visible soon enough by astronomers, so it's a decent prediction. They also differ from the structures predicted in alternative answers to the questions, "are accretion discs entrained to the equators of spinning black holes? what is the mechanism?".

Finally, "observation". Except in X-rays (thanks to Inverse Compton Scattering) we have few direct observations of accretion disc structure. We have not proven that astrophysical accretion happens in discs. There may be non-disc accretion systems, and at least in principle we are not in position to say which is the exception (are accretion discs rare? are non-disc structures rare?).
We do know (thanks to the background luminosity and larger subtended angle) that there are polars, which are very X-Ray bright white dwarfs and neutron stars which channel accretion into columns down their magnetic poles, rather than into discs. There are pulsars which have both this type of columnar accretion and disc accretion, too.
If these compact objects collapse further into black holes, what happens to these columnar accretion structures?

Hopefully astronomers will figure out how to better see known black holes and black hole candidates in various parts of the electromagnetic spectrum. We may also get some ideas about large accretion structures from central-black-hole mergers in distant galaxies, and maaaybe even in open clusters in our own galaxy (the Hyades cluster has been in recent news, and it's close). Also globular clusters in our galaxy like M15 might turn out to have a central black hole with lots of matter liable to be drawn into a close orbit around it.

(Our own central black hole Sgr-A* is not just obscured by dust and gas along our line of sight, it's also really really quiet in the wavelengths which are least obscured; it does not seem to be accreting much of anything. It only got the "*" designation because in radio it stood out strongly against the other things in Sagittarius. Even Jansky noticed it in 1933 on his apparatus <https://en.wikipedia.org/wiki/Karl_Guthe_Jansky#/media/File:...>. But most known central black holes in other galaxies are much brighter in radio than ours).