Examples of finite group schemes over a field which are not affine

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Let $G$ be finite group scheme over a field $k$. What are some examples of $G$ such that it is not affine?

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It is immediate from the definition that any finite group scheme (indeed, any finite scheme) over a field is affine. If a morphism is finite, that means there is an open cover of the base by affine sets whose inverse images are affine and for which the morphism comes from a finite map of rings. When the base is Spec of a field, this just means the domain scheme itself must be affine (and Spec of a finite-dimensional algebra over the field). More generally, any finite morphism is affine, so if the codomain is affine then so is the domain.