While it is, indeed, not visible in the archived check results, digging
into src/contrib/PACKAGES.in reveals that 'parzer' failed the
UBSanitizer check on an Apple M1 machine on June 1st:
https://www.stats.ox.ac.uk/pub/bdr/M1-SAN/parzer/tests/testthat.Rout
Casting a NaN value to an integer is undefined behaviour (with de-facto
different results on x86_64 and ARM processors). There used to be a
check for 'x' being NA_real_, but it seems to have been broken during
refactoring three years ago:
https://github.com/ropensci/parzer/blame/10a8aa68bea8b18a69cc99326e949c5beb144afd/src/pz_parse_parts.cpp#L11-L21
Arguably, the check should be for isnan(x), not only R_IsNA(x): the
latter will still miss non-NA NaN values.
I think that the packages should have had a yellow deadline mark (i.e.
with(tools::CRAN_package_db(), Deadline[Package %in% c('parzer',
'flightsbr')]) should have been returning non-NA values) in the month
that passed. Having a number of packages archived due to a silent
problem with mail delivery is very unfortunate.