uh...what is this thing? i rebooted firefox and had a bar at top mention it.

i clicked the link to read about it but now i'm more confused than before. especially since that wiki page hasn't been updated since september last year.

TL;DR: it's a randomized participation study for Firefox features. You can opt in or out if you're selected for it.

If you open Add-ons (or go to about:addons) > Experiments, you might discover you've participated in some tests without being alerted. Although I haven't noticed anything on my browser called Firefox Shield, I expect its tests would be mentioned there. Apparently, I did some things. I'm on Firefox beta.

Edit: Hmm. Shield Studies might be a separate telemetry source from Experiments. Check your add-ons for Shield Studies. I read that Shield Studies are supposed to uninstall after 7 days, but that might not be the case for all of them. Some Shield Studies can be seen here, although not everything listed is a Shield Study. You can find more detailed information here.

abadbird said:
If you open Add-ons (or go to about:addons) > Experiments, you might discover you've participated in some tests without being alerted. Although I haven't noticed anything on my browser called Firefox Shield, I expect its tests would be mentioned there. Apparently, I did some things. I'm on Firefox beta.

Edit: Hmm. Shield Studies might be a separate telemetry source from Experiments. Check your add-ons for Shield Studies. I read that Shield Studies are supposed to uninstall after 7 days, but that might not be the case for all of them. Some Shield Studies can be seen here, although not everything listed is a Shield Study. You can find more detailed information here.

just checked and there's nothing like that in my add-ons. i don't know why i got that notification bar thing earlier.

Perhaps you were randomly selected to opt-in. My understanding is that you would be presented with a notification of some kind during normal browsing (could be on any webpage) with a button to click to participate. If you click the button, you go to a page like this one where you can agree to the study by downloading the add-on. Conceivably, the notification could prompt you to directly download the Shield Study add-on without taking you to a webpage first.

abadbird said:
You can find more detailed information here]

If you open that link and scroll down, you will see an example of a Shield Study notification that says "Speed up your Firefox (get it now)" and an example of a different opt-in page.

If you didn't agree to download a Shield Study add-on, or if a Shield Study add-on is not installed, then you should not be participating in any of those studies. If you didn't go all the way and download an add-on, you may have "missed your chance" to participate, but I don't see why the study couldn't be found manually and joined if you knew what to look for.

Another telemetry source for Firefox developers is Test Pilot.

I've tried installing everything I've mentioned or linked to because I'm dumb I'm beyond caring about the consequences, and I experienced a range of issues. Some add-ons failed to download/install, some seem to have installed and immediately uninstalled (my browser failed criteria, I guess), one add-on caused some bookmark icons to flash incessantly (GPU bug, probably), and at least one add-on caused my browser's memory consumption to quadruple and/or a memory leak. When I disabled the add-ons to troubleshoot, some of them just uninstalled and took me to a survey. I'm down to three Shield Studies.