It’s probably an SSD for a Fusion Drive setup: https://en.m.wikipedia.org/wiki/Fusion_Drive

It seems to check out for iMac in 2019.

If I recall correctly, it was meant as a measure against fingerprinting. It’s basically one less thing to uniquely define a user based on the info that the browser gives to a website. I’m not sure if it’s still like that, cause it’s been easily a year since I used LibreWolf.

I applaud LibreWolf’s efforts, but the hard-coded timezone makes it unusable for me. Other than that, it’s a great browser. I used it several months until the timezone confusion got the best of me.