CodeParkGrey text with too little contrast against its background
eslint-plugin-jsx-a11y reads your JSX source code. It never renders the page, so it can't know the final colours after CSS is applied. Contrast needs a runtime tool like axe or Lighthouse.
The other three are the tempting wrong answers, because they sound hard to detect. But they are all visible in the JSX. The plugin has rules for them: alt-text, click-events-have-key-events and anchor-is-valid. Linting catches these early in the editor, which makes it a cheap first layer.