Nope, I've never seen that. Iceraven is just Firefox for Android with more extensions enabled, about:config support, and a couple of other minor annoyances fixed.
>>nfried+(OP)
Wait, the post says iceweasel but the link is iceraven, are they the same thing? This was on the default browser one of the times I tried LineageOS, this was back in 2019 or so. I could be misremembering the specific fork.
>>taneq+kU3
I found this about iceweasel, which inclines me to believe that you remembered it correctly, and the grandparent was just mistaken about the name:
> In August 2005,[11] the GNUzilla project adopted the GNU IceWeasel name for a rebranded distribution of Firefox that made no references to nonfree plugins.
> [...]
> The GNU LibreJS extension detects and blocks non-free non-trivial JavaScript.