Hi there,
When it comes to themes and SEO, all we can really do is make sure things are light and fast, which is why we focus so much on that area. The results are based more on your content and the current algorithm that Google is using.
If your content hasn’t changed, and you weren’t doing anything special in Avada, I assume what you’re seeing is a normal fluctuation of the results.
Of course, you should dig into your search console data to see if anything stands out.