Seems to be mainly affecting the LGBTQ+ community.
https://news.gallup.com/poll/147824/adults-estimate-american...
(This is one of my favorite stats.)
For similar reasons, Americans consistently overestimate blacks and Hispanics' share of the US population. They estimate on average that 33% are black and 29% Hispanic when the true figure is less than 13% for each. <https://np.reddit.com/r/todayilearned/comments/3ncaz8/til_th...>