I have copies of two files that preceded the bug:
FreeBSD-15.0-CURRENT-amd64-20250801-0a3792d5c576-279199-disc1.iso
FreeBSD-15.0-CURRENT-amd64-20250801-0a3792d5c576-279199-mini-memstick.img
Checksums at
<https://mail-archive.freebsd.org/cgi/mid.cgi?20250801182357.5F236257B>
do match.
The 20250801 files have been weeded from
<https://download.freebsd.org/snapshots/ISO-IMAGES/15.0/>, and mirrors.
If anyone would like a copy of either file, please contact me off-list.
I might temporarily share via MEGA or whatever.