All the reviews that give it a 5 are bought and paid for. There is no way this film is even close to a 3, either. It's a 1. Why? To make it simple; it's garbage, darling.
The frenetic, nonsense pacing, the horrible writing, the terrible acting, the lukewarm motivations, the atrocious wig, the lack of any coherence—it's almost comical how God-awful Malignant is, except I know it's not meant to be a comedy.
And that's the problem.
Malignant has no idea what it wants to be, just like the protagonist has no idea who she is for much of the film. Sadly, unlike the protagonist, Malignant doesn't have superpowers that allow it to project a better version of itself into our cerebral cortex.