In December 2018, the charity was designated £500,000 in funding by the Big Lottery Fund, to create a national network of local groups. However, the funding was put under review after criticism of the charity, including by anti-trans activist Graham Linehan, who created a post on Mumsnet calling for members of the forum to email their concerns to the National Lottery. In response to this, on 18 January 2019, YouTuber Hbomberguy began a livestream attempting to 101% complete the video game Donkey Kong 64, with a goal of $500 to be donated to Mermaids. The stream became popular and raised over $350,000 USD for Mermaids. Among other guests, the stream featured an appearance by American politician Alexandria Ocasio-Cortez. On 19 February 2019, the National Lottery concluded its review into the charity and announced that it would follow through with the promised donation, stating that "did not find any grounds to withhold the grant.". However, in October 2022, National Lottery funding was paused due to the investigation by the Charity Commission.
