Going back a page no longer costs you the sound. When Firefox restored a page from its back/forward cache, the audio could come back silent until you reloaded it. It comes back working now, with your level still applied.

Levels stop drifting on their own. A level you set while a page was still loading could snap back to whatever was saved for that site, and with remembering turned off a boost could quietly return to 100% by itself after a while. Both are fixed.

The popup is slower to give up. On a busy page it could decide it was not able to run before the page had finished attaching, and then stay that way until you closed and reopened it. It waits now, and corrects itself once the page is ready.

No new permissions.