From Eve Livingston's article that Eden Palmer referenced
In March of this year, former intern Emma Healey publicly criticizeded_ the site’s stance on trans rights and shared private internal communications on the subject. Healey alleged that the “vast majority” of trans discussion on Mumsnet “descends into scaremongering and hate speech,” claiming that the company dismissed staff concerns about the offensive tone of the posts.^
This was illegal doxxing of the IP addresses of members, not "sharing internal communications".
In April, former Mumsnet employee Hannah Woodhead wrote inin Huckck magazinene_: “The anti-trans community on Mumsnet is something of an open secret. It has been present for years, and it appears that there has, for a while, been a lax approach to tackling this particular form of hate speech.”^