Captchas have been restored by a PR shortly before release and almost immediately been removed again by reverting the PR. The PR author has been asked to re-create his PR and then 0.18.0 got released without Captchas.
FYI, I needed to drop all cached files from lemmy.world in chrome afterwards. Otherwise clicking on the top right profile button would shift the entire page down.
/c/mmorpg@lemmy.ml is actually a community I'm subscribed to which has this issue. /c/guildwars2@lemmy.wtf is another example.