I've been reading this article a while ago because I had the same question:
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By their very nature, carousels require the loading of additional images and scripts to achieve their goal. As website performance (loading speed) is a key user experience, and SEO metrics, every second counts. Using a single static image accompanied by HTML text, rather than multiple images, and the scripts required to run a carousel, will always perform better.
In particular, carousels use precious bandwidth on mobile devices at slower connections. We also often find "creep carousel", a situation where content managers continue to add more and more slides without removing the old losers.
The article also shows that there are problems with SEO when using Carousel:
Often, the textual component of a carousel is embedded in the slide of the image on a carousel. This means that a search bot can not read and understand the content and hierarchy of the image content. Although you can (and should) always add alt text to an image, that solution is less than ideal. Alternative image text is expected to describe that image, NOT replacing HTML content. For example, in HTML content, you can have headers, lists, formatting (bold, italic), etc ... None of this is supported by alternative text. Therefore, search engines (and the visually impaired) may have difficulty understanding the structure and content of the slide.
In the article also has several tips on this topic, in addition to the summary I put here, it's worth taking a look!
