New: Alt-Svc HTTP header value information is now shown in the tooltip when the header is part of an HTTP response to provide an indication as to whether a page supports HTTP/3, but isn’t using it for whatever reason.
New: If an unknown HTTP version (i.e., a version other than 3.0, 2.0, 1.1, or 1.0) is encountered, that information should now be reported in the tooltip. (Since I’ve yet to encounter such a page, this functionality isn’t tested.)
Changed: Changed the “Request” tooltip heading to “HTTP Request URL”.
Changed: Changed the “Response” tooltip heading to “HTTP Version”.
Changed: Extraneous information such as the HTTP method (e.g., GET, POST, etc.) and URL fragment identifiers are no longer displayed.
Changed: The HTTP version text now includes a slash (/) character (i.e., “HTTP/3.0”, “HTTP/2.0”, etc.) for consistency with the HTTP/3 draft specification.
Changed: Changed the name of the background script from the generic “background.js” to “HTTP Version Indicator Background Script.js” to make it easier to determine whether errors are emanating from this extension via the Browser Console window.
Fixed: Converted the SVG indicator icons to PNG icons as a workaround for an issue in Firefox 89 beta builds in which the color black is converted to white and other colors are converted to gray thereby rendering the color-based visual cues useless.
Fixed: Changed how events are handled to fix issues with an icon not being displayed for pages that load unusually fast (e.g., example.org); the wrong information being displayed for pages that are the destination of redirects (e.g., via news.google.com); and “browser.tabs.onUpdated.addListener(...) is undefined” error messages being logged to the Browser Console window.

Fixed: Scoped the extension to only execute on http:// and https:// pages.