SEO implications of using f_auto vs always delivering the same format
I'm a bit confused by the differing recommendations I'm seeing from different sources.
On the one hand, I see the value in being able to have a .jpg file extension in the URL, for example, while setting f_auto to ensure that users get the best format for their individual devices.
On the other hand, I've noticed that the Google Images docs for example recommend having the image file extension be the same as its extension in the URL. I've also seen various articles/blogs saying it's best to keep them the same if possible.
Our application is SEO-focused to a significant extent, so I'd like to get this right. My preference would be to specify a file extension in the URL as a fallback (that's how it works, right?) while using f_auto... does this practice have a downside in terms of SEO at all?
Thanks in advance.