Apt Priority

Package: snapd
Pin: release a=*
Pin-Priority: -10

deb [arch=amd64 signed-by=/etc/apt/keyrings/packages.mozilla.org.asc] https://mirrors.tuna.tsinghua.edu.cn/mozilla/apt mozilla main

Package: firefox*
Pin: version 1:1snap1*
Pin-Priority: -1

Package: firefox*
Pin: origin mirrors.tuna.tsinghua.edu.cn
Pin-Priority: 1001

sudo add-apt-repository ppa:mozillateam/ppa

Package: thunderbird*
Pin: version 2:1snap1*
Pin-Priority: -1

Package: thunderbird*
Pin: release a=ppa:mozillateam/ppa
Pin-Priority: 1001