A lot of these are examples of bad prompting (i.e. "build me a website for x y z"). Gradients can be prompted out, same as emoji slop. One line in the prompt / agents.md and you never see those. Color "rainbow" should be avoided by specifying a color palette. In case you don't have one, ask it for one "from literature / best practices" first. LLMs know the theory, but you have to have it in the context for it to be applied.

Misaligned stuff is the prompter's fault. Those should be caught by the human. they're the types of tasks that are fast/cheap to verify.