you’ll have noticed

[keannu]

This kind of "will+have+p.p" is mostly future perfect, but in this case it's presumption for the past, which means like "you probably noticed" considering "If you've ever" in the conditional clause. isn't it?

mo3-49 ex)If you’ve ever had would-be buyers looking around a house, you’ll have noticed their observations about each room are usually limited to: “Hmm, it’s a good size.” or “Hmm, it’s rather small.” Little wonder then that home-improvers are so often fixated on making their rooms appear as spacious as possible.

 

[5jj]

In the right context:

You will know - I am certain that you know.
You will have noticed - I am certain that you have noticed.

 

[BobK]

:up: ... though maybe 'certain' is a bit strong. For example, in a recurring feature in 'I'm Sorry I Haven't A Clue' (very long-lived radio programme), a dialogue between two Scots begins: "Hamish!'/'Dougal!'/'You'll have had your tea.' There it's not certain, but it's making it clear that the presumption has been made.

b