I think there’s more than that in this case, because on Intel the script checks to see if a new image is available, but on ARM it will always pull. The reason given is that ARM always uses a fixed tag. For example, today, we see in the launcher script two possibilities:
image="discourse/base:2.0.20240825-0027"
or
image="discourse/base:aarch64"
and as you see, one of those is maintained carefully as new images are approved, and the other is left to the position of the tag.
The relevant parts of the script are nearly 3 years old. I wonder, is ARM still so experimental that it needs this different handling?
As it turns out, then, the Intel image which will be pulled is presently 15 days old and sits on the 8th page of listings of base images, whereas the ARM image is the latest image and just 17 hours old.