The variation page renders a single variation of a component as well as the validation results (see below). You can open it in a new tab, which renders nothing but the component, which is best for development.
By default, components are tested for accessibility and HTML violations. The accessibility validation uses a local axe-core installation, while the HTML validation uses an external service from https://validator.w3.org/nu/.
https://validator.w3.org/nu/ has a rate limit of max. 10 requests per minute. If you are updating your components often, you might want to deactivate the HTML validation, otherwise your IP will be blocked.