The notice itself isn’t malware, but I’m not sure on the cause. For some reason the Lemmy web client occasionally tries to cache a metric fuckton on iOS Safari (and probably elsewhere but it happens silently), which sounds like something for the devs to look into.

Generally, Lemmy’s 100x better in stability and speed than it was a couple months ago when a bunch of new people started working on it, but before then it was the side project of a handful of people and it showed. EG - The infamous, three-year-old Hexbear instance managed to have the entire picture side of it go down for a couple days because someone uploaded an absurdly large, extremely low quality photo of a North Korean soldier on it. So, there are probably still some issues like that kicking around.