Firefox 91.0.0, and 91.0 ESR, and 78.13.0 ESR

[German]Mozilla's developers have released version 91.0.0 (including ESR version) and 78.13.0 ESR of the Firefox browser on August 10, 2021. The version 91.0.0 is a new development branch of the browser, and the 78.13.0 ESR is a security update, which should eliminate vulnerabilities, but also fix bugs.

Firefox 91.0.0

According to the release notes, version 91.0.0 brings some new features as well as bug fixes and security fixes. Here's a rough overview of what's new: 

• Building on Total Cookie Protection, developers have added more comprehensive cookie deletion logic that prevents hidden data leaks and makes it easy for users to understand which sites store local information (see also).
• Firefox now supports logging in to Microsoft, work and school accounts with Windows Single Sign-On (SSO, see also).
• The simplify page feature when printing is back! When printing, under More Settings > Format, select Simplified if available to get a clear page (see).
• HTTPS-First policy: Firefox Private Browsing windows now try to make all connections to websites secure, and only fall back to insecure connections when websites don't support it (see).
• A new locale has been added: Scottish (sco)
• The address bar now returns "Switch to Tab" results even in private browsing windows.
• Firefox now automatically enables high contrast mode when "Increase contrast" is enabled on macOS.

Firefox is now catching up on almost all user interactions, providing a 10-20% improvement in response time for most user interactions. In addition, some security vulnerabilities rated as high or moderate have been fixed in the new version. Details can be read here in the relevant sections. After the update, the Proton user interface seems to be restored, no matter what the user has set.

Firefox 91.0.0 esr

A Firefox 91.0.0 esr version with one year of long-term support has also been made available. On the web page in question there are notes about what has been changed in the user interface or in the functions compared to the previous ESR variant. 

Firefox 78.13.0 esr

An update to Firefox 78.13.0 esr has also been provided with one year of long-term support with vulnerabilities fixed. 

The new Firefox and the ESR variants can be downloaded from this website for various platforms (the variant is to be selected via the displayed list boxes).