Doing a rebuild on arm64, I saw the following failure:

/bin/bash ./libtool  --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H -I.   -Wdate-time -D_FORTIFY_SOURCE=2 -I./src/common -I./include -Wall -Wextra -Wno-missing-field-initializers -Werror -g -O2 -std=c99 -D_XOPEN_SOURCE=600 -fvisibility=hidden -g -O2 -fdebug-prefix-map=/home/steve/debian/build/kqueue/libkqueue-2.0.3=. -fstack-protector-strong -Wformat -Werror=format-security -c -o src/common/libkqueue_la-kevent.lo `test -f 'src/common/kevent.c' || echo './'`src/common/kevent.c
libtool: compile:  gcc -DHAVE_CONFIG_H -I. -Wdate-time -D_FORTIFY_SOURCE=2 -I./src/common -I./include -Wall -Wextra -Wno-missing-field-initializers -Werror -g -O2 -std=c99 -D_XOPEN_SOURCE=600 -fvisibility=hidden -g -O2 -fdebug-prefix-map=/home/steve/debian/build/kqueue/libkqueue-2.0.3=. -fstack-protector-strong -Wformat -Werror=format-security -c src/common/kevent.c  -fPIC -DPIC -o src/common/.libs/libkqueue_la-kevent.o
src/common/kevent.c: In function 'kevent_dump':
src/common/kevent.c:107:37: error: '%s' directive output may be truncated writing up to 1023 bytes into a region of size between 931 and 1004 [-Werror=format-truncation=]
src/common/kevent.c:98:28:
     return ((const char *) &buf[0]);
                            ~~~~~~~
src/common/kevent.c:107:37:
             "{ ident=%d, filter=%s, %s, %s, data=%d, udata=%p }",
                                     ^~
src/common/kevent.c:107:13: note: using the range [-2147483648, 2147483647] for directive argument
             "{ ident=%d, filter=%s, %s, %s, data=%d, udata=%p }",
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

I can reporiduce just the same on amd64. Using -Werror with newere
compilers...

Hello,

Good morning,

We have gone through your samples from a partner and Here is our  Order
List. Please do bear in mind that we are very much in  need of this
order, quote your competitive prices.

Kindly send the Order confirmation.

Your early reply will be much appreciated.

Best Regards,

Maryanah Erwin.

PT FINDORA INTERNUSA

Jln Pahlawan 66 Kec. Arjawinangun

45162 CIREBON West-Java INDONESIA

tel : +62 231 357334

fax: +62 231 357260

email: marketing@findora.com

Dear submitter,

as the package libkqueue has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1104870

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)