I'm curious the guix version would also build differently on your computer.
You can run for example
guix build vice --no-grafts --check
to build it from source and check the difference. if its different, something like
guix gc -D $(guix build --no-grafts vice); guix build --no-substitutes vice
should delete it and built it from source without using the prebuilt binary.
If it's different then its a reproducibility bug. Some packages are actually
intended to be that way, like atlas, and have substitutable? #f set so that
they are always built and tuned to the cpu it's used on.
On my computer, AMD 5700X, the built is identical to the substitute:
b@jiu ~/code/guix [env]$ guix challenge vice
1 store items were analyzed:
- 1 (100.0%) were identical
- 0 (0.0%) differed
- 0 (0.0%) were inconclusive