This bug appears to have been reported against 'rawhide' during the Fedora Linux 39 development cycle.
Changing version to 39.

Dear Maintainer,

your package has an open Fails To Build From Source bug for Fedora 39.
Action is required from you.

If you can fix your package to build, perform a build in koji, and either create
an update in bodhi, or close this bug without creating an update, if updating is
not appropriate [1]. If you are working on a fix, set the status to ASSIGNED to
acknowledge this. If you have already fixed this issue, please close this Bugzilla report.

Following the policy for such packages [2], your package will be orphaned if
this bug remains in NEW state more than 8 weeks (not sooner than 2023-06-01).

A week before the mass branching of Fedora 40 according to the schedule [3],
any packages not successfully rebuilt at least on Fedora 38 will be
retired regardless of the status of this bug.

[1] https://docs.fedoraproject.org/en-US/fesco/Updates_Policy/
[2] https://docs.fedoraproject.org/en-US/fesco/Fails_to_build_from_source_Fails_to_install/
[3] https://fedorapeople.org/groups/schedule/f-40/f-40-key-tasks.html

From the mock_output.log:

INFO: Package manager dnf5 detected and used (direct choice)
Start: installing minimal buildroot with dnf5
ERROR: Command failed: 
 # /usr/bin/systemd-nspawn -q -M 027a571acd064dd8a31845a7be6e9362 -D /var/lib/mock/f40-build-48244841-5748918-bootstrap/root -a --capability=cap_ipc_lock --bind=/tmp/mock-resolv.znpf_kw5:/etc/resolv.conf --console=pipe --setenv=TERM=vt100 --setenv=SHELL=/bin/bash --setenv=HOME=/var/lib/mock/f40-build-48244841-5748918/root/installation-homedir --setenv=HOSTNAME=mock --setenv=PATH=/usr/bin:/bin:/usr/sbin:/sbin '--setenv=PROMPT_COMMAND=printf "\033]0;<mock-chroot>\007"' '--setenv=PS1=<mock-chroot> \s-\v\$ ' --setenv=LANG=C.UTF-8 --setenv=LC_MESSAGES=C.UTF-8 --resolv-conf=off /usr/bin/dnf5 --installroot /var/lib/mock/f40-build-48244841-5748918/root/ groupinstall srpm-build --setopt=deltarpm=False --setopt=allow_vendor_change=yes --allowerasing --setopt=tsflags=nocontexts
Unknown argument "groupinstall" for command "dnf5". Add "--help" for more information about the arguments.
It could be a command provided by a plugin, try: dnf install dnf5-command(groupinstall)

Dear Maintainer,

your package has an open Fails To Build From Source bug for Fedora 39.
Action is required from you.

If you can fix your package to build, perform a build in koji, and either create
an update in bodhi, or close this bug without creating an update, if updating is
not appropriate [1]. If you are working on a fix, set the status to ASSIGNED to
acknowledge this. If you have already fixed this issue, please close this Bugzilla report.

Following the policy for such packages [2], your package will be orphaned if
this bug remains in NEW state more than 8 weeks (not sooner than 2023-06-01).

A week before the mass branching of Fedora 40 according to the schedule [3],
any packages not successfully rebuilt at least on Fedora 38 will be
retired regardless of the status of this bug.

[1] https://docs.fedoraproject.org/en-US/fesco/Updates_Policy/
[2] https://docs.fedoraproject.org/en-US/fesco/Fails_to_build_from_source_Fails_to_install/
[3] https://fedorapeople.org/groups/schedule/f-40/f-40-key-tasks.html

This was a problem with Koji builders. It's fixed now: https://koji.fedoraproject.org/koji/taskinfo?taskID=112161886