Firefox 138 was released yesterday and wasn't particularly exciting besides enhanced profile management and Tab Groups support... Aside from that it was a pretty basic release. In turn Firefox 139 is now in beta and that release does bring some items worth mentioning like faster HTTP/3 upload performance.

Firefox 139 Beta boasts faster upload performance on HTTP/3 to the point that it's "significantly improved." Especially for HTTP/3 connections involving QUIC 0-RTT resumed connections and high bandwidth and high delay connections, HTTP/3 uploads should be much faster on Firefox 139 than with prior releases.

Some of the other Firefox 139 Beta changes include full-page translation support within Firefox extension pages, PNG images with transparency are now preserved when pasting into Firefox, and support for the "hidden=until-found" attribute for content to be found in the via find-in-page but not otherwise displayed by default.

Downloads and more details on the Firefox 139 Beta release via Mozilla.org .