@Serentty Might be some issues with the source. You can try other sources: https://www.ports.debian.org/mirrors.
加上 [trusted=yes] 就好了
deb [trusted=yes] http://mirrors.perfxlab.cn/debian-ports/ sid main
deb [trusted=yes] http://mirrors.perfxlab.cn/debian-ports/ unreleased main
E: The repository 'http://mirrors.perfxlab.cn/debian-ports sid Release' no longer has a Release file.