I would not call an extension with 5K users, popular. Or did PCWorld confuse it with uBO?
It is, essentially, uBlock Origin for ManifestV3, so if the author confused it for uBO, it wouldn’t be very wrong.
tl;dr: It is very popular, and very trusted.
uBOL may be small compared to its full-fledged counterpart, but Firefox Mobile also has a much smaller browser market share compared to any other[3].
[1] https://twitter.com/gorhill/status/1748763311535948228
[2] https://github.com/uBlockOrigin/uBOL-home/wiki/Frequently-as...
[3] https://gs.statcounter.com/browser-market-share/mobile/world...