I wonder if the prints were since scanned in 4K at the LOC?
In all honesty, probably not. The LOC is a phenomenal institution and the value of work they do preserving our knowledge, history, and art can NOT be overstated.
However, they are a government institution and subject to all the bureaucracy, politics, funding, and budget constraints typical of such governmental trappings.
Private corporations and even private individuals generally have newer, better, more advanced tools and technology at their disposal.
With the exception of classified and/or legally unobtainable military tech, the wealthy private sector almost ALWAYS has better stuff than the government. And film preservation is not any different.
Though I will say the cold storage film vaults of the LOC are top notch (mostly because they were built and donated by a wealthy member of the Packard family - as in Hewlitt Packard) and thus it’s name: the Packard Campus.