Firefox Beta and Developer Edition
Release Notes

Users on macOS and Linux are now given the option to close only the current tab if the Quit keyboard shortcut is used while multiple tabs are open in the window.

Firefox now includes new safeguards to prevent sites from overwhelming the Back history by spamming numerous consecutive visits over a short time.

To help Mozilla find and fix crashes, you can opt into automatically sharing Firefox for Android crash reports by checking the new Data Collection setting "Automatically submit crash reports".

The "Copy Without Site Tracking" menu item was renamed to "Copy Clean Link" to help clarify expectations around what the feature does. "Copy Clean Link" is a list based approach to remove known tracking parameters from links. This option can also now be used on plain text links.

Linux binaries are now provided in XZ format, replacing the previous BZ2 format, offering faster unpacking and smaller file sizes. Blog Post

The attribute values which indicate the coordinates of PointerEvent may now be fractional values rather than only integers. This allows web apps to handle the events with higher-precision coordinates when the target element is transitioned by CSS and/or the viewport is zoomed.

The behavior of mouseenter, mouseleave, pointerenter and pointerleave events was changed for improved spec compliance when the last mouseover or pointerover event target is removed.

Added support for the WebAuthn getClientCapabilities() method.