In most cases, the ledger can be interrupted between joists to accommodate protrusions from your house. With me, there is generally no cost for doing so.

Also note here the flashed top and sides of the ledger. The sides extend below the ledger, where it also covers the vulnerable spot where the finish trim meets the ledger board. The deck is set about 2 inches below the patio door so that snow and ice are less of a a problem with the screen track. Although the vent is higher than the framing, the thickness of the decking will cover most of the metal.

It is not a great idea to fold over the edge of a joist hanger in order to butt it up to the end of a ledger. Instead, move it in about 1.5 inches and use the fascia or rail post to conceal the metal.