I needed to add CFLAGS+=' -ffat-lto-objects' in order for cef-sys-dll to build on my system.

New PKGBUILD would be something like:

# Maintainer: Andrew Rabert <ar@nullsum.net>
#/home/solarisfire/.cache/yay/jellyfin-desktop-git/PKGBUILD
pkgname=jellyfin-desktop-git
pkgver=0.r900.455d4ac
pkgrel=1
epoch=1
license=('GPL-2.0-only')
pkgdesc="Jellyfin Desktop Client"
arch=('x86_64')
url="https://github.com/jellyfin/jellyfin-desktop"
depends=(
    'cef'
    'jellyfin-desktop-libmpv-git'
    'libglvnd'
    'libxcb'
    'libxkbcommon'
    'libxkbcommon-x11'
    'systemd-libs'
    'wayland'
    'xcb-util-cursor'
    'xdg-utils'
)
makedepends=(
    'git'
    'plasma-wayland-protocols'
    'python'
    'rust'
    'vulkan-headers'
    'wayland-protocols'
)
provides=('jellyfin-desktop')
conflicts=('jellyfin-desktop')
replaces=('jellyfin-desktop-cef-git')
source=("git+${url}.git")
sha256sums=('SKIP')
options=(!debug)

pkgver() {
    cd jellyfin-desktop
    printf "0.r%s.%s" "$(git rev-list --count HEAD)" "$(git rev-parse --short=7 HEAD)"
}

build() {
    cd jellyfin-desktop

    env -u RUSTC_WRAPPER -u SCCACHE_DIR \
    cargo run --manifest-path src/xtask/Cargo.toml -- build \
        --cef-path /usr/lib/cef \
        --external-mpv /opt/jellyfin-desktop/libmpv
}

package() {
    cd jellyfin-desktop

    env -u RUSTC_WRAPPER -u SCCACHE_DIR \
    cargo run --manifest-path src/xtask/Cargo.toml -- install \
        --skip-build \
        --cef-path /usr/lib/cef \
        --external-mpv /opt/jellyfin-desktop/libmpv \
        --prefix "$pkgdir/opt/jellyfin-desktop"

    # Symlink to /usr/bin
    install -dm755 "$pkgdir/usr/bin"
    ln -s /opt/jellyfin-desktop/jellyfin-desktop "$pkgdir/usr/bin/jellyfin-desktop"

    # Icon
    install -Dm644 resources/linux/org.jellyfin.JellyfinDesktop.svg \
        "$pkgdir/usr/share/icons/hicolor/scalable/apps/org.jellyfin.JellyfinDesktop.svg"

    # Desktop entry
    install -Dm644 resources/linux/org.jellyfin.JellyfinDesktop.desktop \
        "$pkgdir/usr/share/applications/org.jellyfin.JellyfinDesktop.desktop"

    # License
    install -Dm644 LICENSE "$pkgdir/usr/share/licenses/$pkgname/LICENSE"
}

Getting this error on install.

==> Starting build()...
CMake Error: The source directory "/home/solarisfire/.cache/yay/jellyfin-desktop-git/src/jellyfin-desktop" does not appear to contain CMakeLists.txt.
Specify --help for usage, or press the help button on the CMake GUI.
==> ERROR: A failure occurred in build().
    Aborting...
 -> error making: jellyfin-desktop-git-exit status 4
 -> Failed to install the following packages. Manual intervention is required:
jellyfin-desktop-git - exit status 4

If you're getting an error like this: Check failed: !strcmp(api_hash, CEF_API_HASH_PLATFORM). API hashes for libcef and libcef_dll_wrapper do not match. CEF was likely updated on your system so you'll need to rebuild this package.

This new client has been decently stable for me lately and is a big improvement from the old code base.

Use jellyfin-desktop instead of this version for some weird reason every comment on the git forces an update for shelly.

is it me or this package,in comparation of the jellyfin-desktop one doesn't have the TV,Desktop,Windowed and Fullscreen flags?Does anyone have the solution for that?

If you are getting "CEF version mismatch" while building this, you need to uninstall jellyfin-desktop-libcef-bin. Otherwise, the build will use CEF from that package instead of cef.

Both the jellyfin-desktop and jellyfin-desktop-git AUR packages are officially maintained by upstream :)

well, that's kind of the question, whether it's a packaging issue or an upstream issue. I tried building myself, and succeeded, to test, but the program wouldn't open at all - get segfaulted, just like when i build the jellyfin package (without the git). So I can't tell. I can still put in a bug report but i'd rather be certain first that it's really an upstream issue.