It’s not new that electromagnetic waves can produce gravitational fields, i.e. distort spacetime geometry-that’s a well-known consequence of Einstein’s equations.

In practice, though, since matter-in the present case electromagnetic fields-affects spacetime through its energy-momentum tensor and the coupling is given by Newton’s constant, it’s just not possible for sparks generated by tabletop experiments to affect the spacetime geometry in any meaningful way. It suffices to compute the RHS of Einstein’s equations for such a case and check by how much it can differ from zero...

Are you sure it is the EM field density that is doing the magic or the flow of field-emitted electrons producing the plasma?

I would rather go with the interaction of light with the plasma - a region with index of refraction not equal to 1 changing the optical path of the beam, therefore nothing to do with gravitation.

“..Is this legitimate electromagnetism - gravitation connection or a hoax to pump up the issuing company? .....”Article Experimental Spacetime Distortion: Generating Gravitational” ....”

Really Gravity fundamentally is nothing else than one of fundamental Nature forces, and - as the other, i.e. Weak, Electric, Nuclear/Strong, Forces - is [mutially] functionally different from other Forces. So Gravity by no means, if isn’t extremely exotically strong, affects on other Forces acting. Including, though electromagnetic and gravitational interactions act fundamentally always in parallel, since everything [besides Forces mediators] have Gravity charges, in Matter everything attracts gravitationally everything, but any other Forces affect on Gravity only by that at their acting inertial rest masses of interacting material objects can change; and so, though inertial and gravitational masses are fundamentally different, the masses are fundamentally equivalent [why? - see the Shevchenko-Tokarevsky’s Planck scale informational physical model,

https://www.researchgate.net/publication/367397025_The_Informational_Physical_Model_and_Fundamental_Problems_in_Physics , section 6.“Mediation of the fundamental forces in complex systems”] Gravity interactions depend only by this ways on other Forces acting, but this is completely negligible minorities.

Besides – see the link above - in the SS&VT model it is rigorously scientifically proven that Matter’s spacetime is absolute, and so it fundamentally cannot be impacted by anything in Matter and impact on anything in Matter. So, though Gravity and Electric Forces are rather similar, and practically for sure accelerated masses radiate gravitational waves - as accelerating electric charges radiate EM waves, but these waves by no means are some “Spacetime Distortions”.

At that Gravity is extremely weak Force, and so really tangible ways are radiated only at large acceleration of large [~ star] masses, and so, say, this in [Abstract of the quoted paper]

“..This paper discusses our observations of gravitational wave generation through the rapid formation of high-energy density fields created by electrically driven spark gaps. Leveraging laser interferometry, this research investigates whether spacetime distortions are produced within the spark-gap plasma.......”

- looks as is too bold claim. Besides that spacetime distortions by no means are produced in this case, the really produced some G-waves are so extremely weak that by no means can be really observed.

Cheers