There are words of caution in the PDF report. https://arxiv.org/abs/2207.11909
, and PDF link, 2207.11909.pdf (arxiv.org)
The abstract states, "While there remains uncertainty in the high-mass end of the Pop III IMF, here
we propose that the larger amount of iron in ULAS J1342+0928 was supplied by a pair-instability
supernova (PISN) caused by the explosion of a massive Pop III star in the high-mass end of the
possible range of 150-300 Msun."
The paper states, "If the initial mass function (IMF) of the hypothetical Pop III stars extended to masses as low as ~ 1 Msun 1977; Sabano & Yoshii 1977; Yoshii & Sabano 1980; Yoshii & Saio 1986; Nakamura & Umemura 1999, 2001; Omukai & Yoshii 2003; Susa et al. 2014; Ishiyama et al. arXiv:2207.11909v1 [astro-ph.GA] 25 Jul 2022 2 Yoshii et al. 2016; Dutta et al. 2020), their lifetimes would be as long as the age of the Galaxy, and they would survive to be observed at the present day. Contrary to expectation, despite the great observational eforts made during the past four decades1, no single star without detectable metals has been found anywhere in the Galaxy."
All Population III stars are *hypothetical* and we have so far, no direct spectrum showing they existed in nature. All Population III stars must form from *hypothetical* BBN gas clouds created with zero metal content, something not seen as far as I know.
As the paper concludes, "The existence of a massive Pop III star of PISN progenitor at high redshift, if confirmed, may also impact ongoing searches for signatures of massive Pop III stars in the Galaxy...
Discovering such stars by new generation surveys may result in eventual derivation of the Pop III IMF in the Galaxy, complementing similar approaches based on future observational studies of quasars at high redshifts."
It seems BBT has more work when it comes to verify that BBT pristine gas clouds formed that the universe evolved out of and then later a generation of Population III stars formed, avoiding problems with lower mass Population III stars when the IMF is poorly constrained apparently.