Feature Request: Tie review queue extensions to the contributor's account, not to their browser (and thus their device).
Per The Complete Rate-Limiting Guide, the limit per contributor is extended to "40 reviews per queue per day if the queue size is 1000 or more (150 on Stack Overflow)"—assuming, of course, the queue doesn't subsequently recede below a lower threshold (≈120 on Stack Overflow).
This extension, however, appears to be tied to a specific browser, and not just the contributor's account. As such, if I am allotted the extension on one browser, then switch to another browser after the queue size has receded below 1000 (or 150 on Stack Overflow), I won't be able to continue my reviews on that browser—even if the queue size remains above the lower threshold. I assume this might be tied to a session variable?
Update: This is not due to the queue being reduced between switching browsers; I can go back-and-forth with one consistently showing a limit of 40 (and accepting reviews), and another showing a limit of 20 (and thus not presenting new reviews). Next time, though, I will need to confirm that the cached queue size is the same between browsers.
Update: There's skepticism in the comments about whether this behavior even exists. I will attempt to document this with screenshots next time. In the meanwhile, I'd encourage members of the community to try to reproduce this themselves the next time they're granted a rate-limit extension.
Why is this even a problem?
If I am allotted the extension while using a mobile device, I want to switch to a desktop device (if available) so it's easier to write comments or make edits. On Stack Overflow, at least, queues like Low Quality Posts, First Answers, and Late Answers rarely exceed the extension threshold for long, due to the number of reviewers. As such, that extension is effectively restricted to a single device.
I don't expect most people check the review queue unless they're on a device where they're able to commit to doing reviews, so this probably isn't a widespread problem. And, of course, from a platform perspective it doesn't really matter so long as the queues are handled by someone. Nevertheless, I find the limitation unexpected, and it can encourage performing reviews on suboptimal devices. (In my case, that means writing fewer comments, and only prioritizing the most critical edits, since e.g. typing backticks for inline code references is tedious on most mobile keyboard layouts.)
Given this, I wouldn't consider this a high priority—but it's nice-to-have if it's a relatively simple fix.