I believe it was both. There were “Q drops” on both 4chan and 8chan, but also 8chan would have never been popular without 4chan. What made 8chan different from other image boards is that it allowed users to make their own boards similar to how reddit allows you to make subreddits. In 2014, Moot (4chan admin) became tired of the community that he created and decided to ban every mention of gamergate. 4chan users had bots to spam “exodus” messages on 4chan, telling other users to moved to 8chan. In 2015, Moot sold the website and I think many of the users returned.
I believe it was both. There were “Q drops” on both 4chan and 8chan, but also 8chan would have never been popular without 4chan. What made 8chan different from other image boards is that it allowed users to make their own boards similar to how reddit allows you to make subreddits. In 2014, Moot (4chan admin) became tired of the community that he created and decided to ban every mention of gamergate. 4chan users had bots to spam “exodus” messages on 4chan, telling other users to moved to 8chan. In 2015, Moot sold the website and I think many of the users returned.