Proper porch flashing?

Saw this today. Vinyl sided house. Concrete front porch. Could not see any flashing from the outside because the vinyl was tight agains the wall. From the crawl space, against the house wood structure, I saw what looked like that fiber-board material and felt paper and tyvek-type house wrap. Didn’t see any metal flashing. House is 3 years old.

What are the requirements for flashing a porch? Is metal required? I don’t think house wrap qualifies. Thanks.

Attached photo shows the metal frame for the concrete porch, the fiberboard, felt paper, and tyvek, and the wood floor framing against that.

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First opinion in…
I see no issue , though I assume the moisture barrier continues past where it appears to end in the photo.