Firefox Beta and Developer Edition
Release Notes

Added support for setting a default zoom level applicable for all web content, regardless of site. This option is available in about:preferences under "Language and Appearance" and can be scaled up or down from 100% as needed.

High-contrast mode has been updated to allow background images. To maintain readability and ensure sufficient contrast, visible text in high-contrast mode will be backplated by the theme's background color.

Improved audio quality when playing back audio at a faster or slower speed.

Fix for MFSA 2020-03 included in Firefox Desktop and DevEdition 73.0b2 builds and newer.

In addition to Cloudflare (which remains the default when DNS over HTTPS is enabled) and custom DNS over HTTPS provider options, users now have the option of selecting NextDNS as the Firefox DNS over HTTPS resolver via the Network Settings dialog in Preferences.

Improved auto-detection of legacy text encodings on old web pages which don’t explicitly declare the text encoding.

Users with 0patch security software may encounter crashes at startup after updating to Firefox 73. This will be fixed in a future Firefox release. As a workaround, an exclusion for firefox.exe can be added within the 0patch settings.