Packer says I'm outta space, but I have lots left...?

I’ve been running a packer build environment without a hitch for almost 2 years. I’ve suddenly started getting an error that my TMPDIR doesn’t have enough space. I’ve tried setting TMPDIR to /packer and creating /packer, which has about 100+ GB of free space, but I’m still getting the error…
[Container] 2021/11/23 20:22:24 Running command export TMPDIR=/packer
[Container] 2021/11/23 20:22:25 Running command echo {TMPDIR} /packer [Container] 2021/11/23 20:22:25 Running command mkdir {TMPDIR}
[Container] 2021/11/23 20:22:25 Running command df -h
Filesystem Size Used Avail Use% Mounted on
overlay 284G 125G 159G 45% /
tmpfs 64M 0 64M 0% /dev
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/nvme0n1p1 284G 125G 159G 45% /etc/hosts
shm 512M 0 512M 0% /dev/shm
tmpfs 1.9G 0 1.9G 0% /proc/acpi
tmpfs 1.9G 0 1.9G 0% /sys/firmware
[Container] 2021/11/23 20:22:25 Running command df -h /tmp
Filesystem Size Used Avail Use% Mounted on
overlay 284G 125G 159G 45% /
Then I run packer…
a df from inside the packer environment also shows plenty of space…
df -hl
Filesystem Size Used Avail Use% Mounted on
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.5M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/nvme0n1p2 10G 993M 9.1G 10% /
tmpfs 375M 0 375M 0% /run/user/1000

And then I get:
Build ‘amazon-ebs’ errored after 19 minutes 2 seconds: Error uploading script: Error copying input data into local temporary file. Check that TEMPDIR has enough space. Please see https://www.packer.io/docs/other/environment-variables#tmpdirfor more info. Error: connection reset
(Not that the URL above generates a 404…)

==> Wait completed after 19 minutes 2 seconds

==> Some builds didn’t complete successfully and had errors:

→ amazon-ebs: Error uploading script: Error copying input data into local temporary file. Check that TEMPDIR has enough space. Please see https://www.packer.io/docs/other/environment-variables#tmpdirfor more info. Error: connection reset

==> Builds finished but no artifacts were created.
and a df after the build shows:
[Container] 2021/11/23 20:41:29 Running command df -h

Filesystem Size Used Avail Use% Mounted on
overlay 284G 125G 159G 45% /
tmpfs 64M 0 64M 0% /dev
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/nvme0n1p1 284G 125G 159G 45% /etc/hosts
shm 512M 0 512M 0% /dev/shm
tmpfs 1.9G 0 1.9G 0% /proc/acpi
tmpfs 1.9G 0 1.9G 0% /sys/firmware
[Container] 2021/11/23 20:41:29 Running command df -h /tmp
Filesystem Size Used Avail Use% Mounted on
overlay 284G 125G 159G 45% /

And a listing of TMPDIR shows no artifacts in it…
[Container] 2021/11/23 20:41:29 Running command ls -l ${TMPDIR}
total 0

So I’m kind of at a loss as to what’s going on here…Can anyone shed some light? Thanks!