emerge --ask --update --deep --changed-use --with-bdeps=y --keep-going --verbose @world --with-bd
These are the packages that would be merged, in order:

Calculating dependencies  ... done!
[ebuild     UD ] x11-themes/adwaita-icon-theme-42.0_p2::dantrell-gnome-42 [43_p1::gentoo] USE="branding" 16’724 KiB

Total: 1 package (1 downgrade), Size of downloads: 16’724 KiB

Would you like to merge these packages? [Yes/No]

>>> Verifying ebuild manifests

>>> Emerging (1 of 1) x11-themes/adwaita-icon-theme-42.0_p2::dantrell-gnome-42
 * adwaita-icon-theme-42.0.tar.xz BLAKE2B SHA512 size ;-) ...                                         [ ok ]
 * tango-gentoo-v1.1.tar.gz BLAKE2B SHA512 size ;-) ...                                               [ ok ]
>>> Downloading 'https://mirror.init7.net/gentoo/distfiles/51/adwaita-icon-theme-41.0.tar.xz'
--2023-01-08 15:48:41--  https://mirror.init7.net/gentoo/distfiles/51/adwaita-icon-theme-41.0.tar.xz
Resolving mirror.init7.net... 109.202.202.202, 2001:1620::1620
Connecting to mirror.init7.net|109.202.202.202|:443... connected.
HTTP request sent, awaiting response... 404 Not Found
2023-01-08 15:48:41 ERROR 404: Not Found.

>>> Downloading 'http://mirror.init7.net/gentoo/distfiles/51/adwaita-icon-theme-41.0.tar.xz'
--2023-01-08 15:48:41--  http://mirror.init7.net/gentoo/distfiles/51/adwaita-icon-theme-41.0.tar.xz
Resolving mirror.init7.net... 109.202.202.202, 2001:1620::1620
Connecting to mirror.init7.net|109.202.202.202|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2023-01-08 15:48:41 ERROR 404: Not Found.

>>> Downloading 'rsync://mirror.init7.net/gentoo/distfiles/51/adwaita-icon-theme-41.0.tar.xz'
rsync: [sender] link_stat "/distfiles/51/adwaita-icon-theme-41.0.tar.xz" (in gentoo) failed: No such file or directory (2)

sent 8 bytes  received 133 bytes  282.00 bytes/sec
total size is 0  speedup is 0.00
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1835) [Receiver=3.2.4]
rsync: [Receiver] read error: Connection reset by peer (104)
>>> Downloading 'https://download.gnome.org/sources/adwaita-icon-theme/42/adwaita-icon-theme-41.0.tar.xz'
--2023-01-08 15:48:41--  https://download.gnome.org/sources/adwaita-icon-theme/42/adwaita-icon-theme-41.0.tar.xz
Resolving download.gnome.org... 8.43.85.3, 8.43.85.5, 8.43.85.4
Connecting to download.gnome.org|8.43.85.3|:443... connected.
HTTP request sent, awaiting response... 404 Not Found
2023-01-08 15:48:42 ERROR 404: Not Found.

!!! Couldn't download 'adwaita-icon-theme-41.0.tar.xz'. Aborting.
 * Fetch failed for 'x11-themes/adwaita-icon-theme-42.0_p2', Log file:
 *  '/var/tmp/portage/x11-themes/adwaita-icon-theme-42.0_p2/temp/build.log'

>>> Failed to emerge x11-themes/adwaita-icon-theme-42.0_p2, Log file:

>>>  '/var/tmp/portage/x11-themes/adwaita-icon-theme-42.0_p2/temp/build.log'

 * Messages for package x11-themes/adwaita-icon-theme-42.0_p2:

 * Fetch failed for 'x11-themes/adwaita-icon-theme-42.0_p2', Log file:
 *  '/var/tmp/portage/x11-themes/adwaita-icon-theme-42.0_p2/temp/build.log'
 *
 * The following package has failed to build, install, or execute postinst:
 *
 *  (x11-themes/adwaita-icon-theme-42.0_p2:0/0::dantrell-gnome-42, ebuild scheduled for merge), Log file:
 *   '/var/tmp/portage/x11-themes/adwaita-icon-theme-42.0_p2/temp/build.log'