Vacation doesn’t do anything except prevent buyers from starting new orders. That’s it.
When you go on vacation mode, your gig won’t display in search results, but it will still display on your seller profile. Buyers can’t start a new order, but in place of the “Order Now” button, they’ll see a “Notify” button that lets them know when you’ve returned.
Vacation mode doesn’t do anything to your gig that doesn’t already happen as a result of not making sales. If your gig was turned on as usual and you just aren’t making any sales, that’s the same thing as being on vacation mode.
I use vacation mode to take a day off from work every week, and it hasn’t hurt me at all. I’ve even gone on vacation mode for two weeks and found that my ranking was untouched. In fact, one time I went on vacation mode for four days and when I came back my seller ranking had actually gone up.
At any rate, don’t worry. If you still want to do business while on vacation, you can still send custom offers and message with clients who’ve already messaged you in the past. Relax, it’s no big deal.