Can anyone point to an actual reputable source that has any details about what specifically got leaked, and how? Instagram has way more users, so it's very odd that only 17.5M get "leaked". Just honestly feels like this is overblown and it's again just scraped data or something.
The original Malwarebytes tweet is incredibly generic.
probably some kind of plugin or app they logged into via instagram but I am not sure what kind of integrations there are, or could it be regional for some reason?