Tor Browser is based on Firefox-ESR, while Librewolf is based on Firefox-Release. Because of this, they do not have identical features and preferences. Tor Browser and Mullvad Browser are designed for stability and minimal customization for the purpose of blending in with other users. Librewolf is designed to receive new features, better privacy defaults than standard Firefox, and allow users to more easily configure preferences. All of these browsers are valid options for privacy-minded people, depending on personal preferences, including separating activities/identities between different browsers. Container tabs are certainly good for privacy, and hopefully the feature can one day be used in private browsing mode.