Hello,

Apparently I found a bug! From what I understand, not enabling 
substitutes should lead to building from source. Authorizing 
ci.guix.gnu.org and bordeaux.guix.gnu.org makes this bug disappear.

The final lines before the backtrace are:
 > guix substitute: warning: download from 
'https://ci.guix.gnu.org/nar/zstd/4gvgcfdiz67wv04ihqfa8pqwzsb0qpv5-guile-3.0.9' 
failed: 504, "Gateway Time-out"
 > retrying download of 
'/gnu/store/4gvgcfdiz67wv04ihqfa8pqwzsb0qpv5-guile-3.0.9' with other 
substitute URLs...

Please find below my system information. The complete bug logs are attached.

Best regards,

Pascal Quach

[1] System information
-----------------------------------------------------------------------
DESKTOP-E9O1UFT:/# guix describe
Generation 2    Mar 10 2024 10:06:41    (current)
   guix 67960be
     repository URL: https://git.savannah.gnu.org/git/guix.git
     branch: master
     commit: 67960be52e01f8bd169dcff5985c4af2c5f87f91
DESKTOP-E9O1UFT:/# guix describe -f channels
(list (channel
         (name 'guix)
         (url "https://git.savannah.gnu.org/git/guix.git")
         (branch "master")
         (commit
           "67960be52e01f8bd169dcff5985c4af2c5f87f91")
         (introduction
           (make-channel-introduction
             "9edb3f66fd807b096b48283debdcddccfea34bad"
             (openpgp-fingerprint
               "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA")))))
DESKTOP-E9O1UFT:/#
-----------------------------------------------------------------------

[2] Bug log attached