google 上的讨论都是辣鸡，最简单粗暴的还是得用我这个方法，出现这个问题可能是文件系统里被大量修改过文件权限，导致系统中的文件权限混乱。
W: Download is performed unsandboxed as root as file '/var/lib/apt/lists/partial/mirrors.tuna.tsinghu
a.edu.cn_debian_dists_bullseye_InRelease' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13:
Permission denied)
给 _apt 账户 root 权限就行，省事。
_apt:x:0:65534::/nonexistent:/usr/sbin/nologin