FWIW, I've seen archeologists use soil samples in similar ways and I've had the same questions. At least at times, it's seen as legimate; that's all I know.
The link is to an online Version of Record before inclusion in an issue that's dated October 2023 .. it's rather early to be claiming this is an article widely accepted by the archaelogical community.
Danny Hilman Natawidjaja writes articles such as this every few years, they aren't highly regarded but they are on record, the fact of being published in no way translates to "having passed peer review" beyond the bar of lacking obvious typos.
His past speculations about hidden chambers as evidence of human activity are generally considered as possible evidence of voids most likely related to chambers and tubes in an ancient volcanic site - which a great many remnant volcanoes have.
Do you happen to be in that field (because you seem to know a lot)?
Peer reviewed here means that articles get a once over for gross errors and that conclusions or interpretations that many people in a field might deem to be far fetched still get published and peers can write in and raise issues in review letters, etc.
This is an article that's in an online free for all advance viewing queie - I'd have to check again to see if it even makes the print copy.
I've worked in geophysical exploration and mapping so I understand the data, the instruments, and the way that cooling volcanic flows create large amounts of what appears to be "machined" rocks that fractures in line with internal crystal stucture.
eg: https://askanearthspacescientist.asu.edu/top-question/column...
The site in question here has been worked by humans for sure - but it's unlikely humans crafted a vast pyramid like complex here, and there's no reason to assume humans created any voids, chambers, or deep tunnels that show up on various scans.
https://onlinelibrary.wiley.com/doi/10.1002/arp.1912
https://onlinelibrary.wiley.com/page/journal/10990763/homepa...
Having no expertise myself, I know it's still easy to shoot down anything. That's why I always look to people with expertise, who know what's significant and what's not, because everything in the world is flawed.