This is an intriguing but very preliminary result.

Basically they've found four globular clusters in very close proximity to each other, a few arcseconds apart and without an associated host galaxy. You might get the odd one or two wandering around after being torn from their parent galaxies by some interaction or other, but four is extremely unlikely. So one possibility is that they're part of a dark galaxy in which all the optical emission is in the globular clusters. This would be weird since the highest mass fraction in globular clusters is around 10-20%. This might have been higher when those galaxies were formed, but over time stars should be lost from the clusters to fill in the gap.

That this hasn't happened here would make this extremely weird unless it's just formed. In which case there ought to be plenty of gas lying around... but here things get immediately dubious. There's a possible parent galaxy not all that far away and it's not clear to me why this isn't the most obvious interpretation - they mention it's discussed in a (much longer) earlier paper, but that looks excessively technical, and they don't actually say why they seemingly don't think this is very likely.

Additionally, they show what the diffuse light would look like in their data if it comprised the same stellar mass as in the globular clusters. It would be detectable, but just barely, so this doesn't look like they've achieved a very strong constraint on the diffuse emission to me. As they say, it wouldn't have to be much more diffuse to be completely undetectable.

Much more interesting than the deep optical data they have here would be measurements of the gas and the velocities of the clusters. If they're all at similar velocities that would be compelling evidence that they're physically associated, and if there's lots of gas, that would argue in favour of a recent origin. As it is, without having read their earlier paper, I think it's more likely that these are just clusters in the halo of the nearest galaxy and nothing unusual.

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https://arxiv.org/abs/2405.12907