For users who have “DNS over HTTPS” enabled—which you should for better browser privacy and security—this update fixes a bug that caused some sites that don’t support HTTPS to fail to load.
It also fixes another networking bug: unexplained loss of all network connectivity when the built-in VPN is enabled. The built-in VPN, which was introduced in Firefox 149, is a good free option for hiding your IP address and location while browsing the web, although it isn’t as secure or feature-rich as some of the best VPN services.
Firefox now has better memory and CPU usage when large JPEG files are shrunk down to fit a page, which should help with web browsing performance on weaker machines and hardware.
The rest of the release notes address other situational bugs, like subtitles sometimes not appearing in Picture-in-Picture mode as well as Firefox sometimes blocking an auto-hiding taskbar on Windows.
In about two weeks, Firefox 157 will be released. That update should add support for JPEG XL (JXL), a modern image format that offers the same quality as JPEG at a significantly smaller size. Although JPEG XL was launched in 2021, Safari is the only browser to support it yet. For a short period, Chrome also supported it, but that ended in 2022.