If you were familiar with far-right extremists before Reddit gave them a comfy little platform, it was painfully obvious.
Sticking to vocabulary only, terms like "cuck" becoming their favourite insult was straight from neo-nazi circles, where it very deliberately meant "race traitor" -- someone who would let a black man fuck their wife.
Since it had the most plausible deniability behind it, "cuck" survived about as long as "alt-right" did, before it became obvious to even the dullest of fucks that it was all just neo-nazis.
But scattered around that, you had terms like "Zionists" and "ethnostate" that aren't inherently Nazi terms but are neo-nazis go-to problem and solution. You had outright dogwhistles like (((Soros))) and 1488. You had preferred slurs for women and minorities that came straight from places that were openly far-right, Holocaust advocates.
You also had various versions of the same old Protocols/Mein Kamph conspiracy theories, custom built for internet reactionaries. Hell, the anti-Hillary frenzy escalated to accused the Democrats of blood libel for fucks sake -- one of the oldest antisemitic conspiracy theories there is.
Most of these came and went as they carefully balanced remaining "mask on". If it became too much of a give away, it was retired and replaced. These days, they know to not even name their movement, because it makes it harder to attack. The "alt-right" is now just "Republicans" so they can hide their extremism behind moderates.
Anyway, fuck the lot of them. Reddit providing a platform for groups like neo-nazis and anti-vaxxers has likely caused more social damage than anything on the internet to date.