Google's John Mueller said that when it comes to links within iFrames, Google can interpret those links in multiple ways. So if you want Google to follow a link a specific way, then don't set up your links in a way that can confuse Google.
The question asked was by @dejanseo who asked "Page [a] embeds an iframe [b] which links to page [c]. How do you think Google interprets this? What are the chances of this counting in some way as an implicit link from [a] to [c], in addition to [b] to [c]?"
John Mueller from Google said it can go either way. He said "It's possible that it could go either way." "From a technical point of view, if there's something you want to link to, just link to it in a way that doesn't require additional interpretation & guessing," John added.
Page [a] embeds an iframe [b] which links to page [c].
— DEJAN (@dejanseo) December 16, 2018
How do you think Google interprets this? What are the chances of this counting in some way as an implicit link from [a] to [c], in addition to [b] to [c]?
It's possible that it could go either way. From a technical point of view, if there's something you want to link to, just link to it in a way that doesn't require additional interpretation & guessing.
— 🍌 John 🍌 (@JohnMu) December 17, 2018
John then added that his response was a cautious one:
I'm just being cautious. More people have taken my quotes out of context than Barry has.
— 🍌 John 🍌 (@JohnMu) December 17, 2018
We do know Google can index content within iFrames.
Forum discussion at Twitter.