  It has been suggested that black hole microstates in string theory may have
"no interiors". The arguments of arXiv:2312.14108 suggest that even if this
were the case, conventional bulk EFT should be valid at the horizon for black
holes that are not too old. Here, we explore the validity of bulk EFT for young
black holes from a different perspective, by considering the gravitational
collapse of scalar moduli. This builds on arXiv:2003.05488, which studied the
numerical collapse of a scalar field in a Choptuik-like set up. Evidence was
presented there for two observations -- (a) For every scalar profile that
results in collapse, the scalar field undergoes trans-Planckian variation, (b)
Every trans-Planckian scalar motion is hidden behind an apparent horizon. The
results of arXiv:2003.05488 were mostly obtained in regimes close to critical
collapse, where scale-separation was difficult to achieve. In this paper, we
study the same system in super-critical regimes. This allows us to study the
localization properties of scalar variations inside the apparent horizon by
separating the horizon and singularity scales. We find strong evidence that the
$\mathcal{O}(1)$ scalar variation is localized around the curvature divergence,
and is hierarchically well-separated from the apparent horizon. Because
$\mathcal{O}(1)$ scalar movement is associated to the breakdown of bulk EFT
according to the swampland distance conjecture, this is an indication that bulk
EFT is well-behaved in the interiors of young black holes. Our results suggest
the perspective that cosmic censorship is a mechanism for preserving bulk EFT
between the horizon and the singularity.
