Just a DP for using Airbnb GC for an existing reservation (which was reserved with a CC). It was my understanding that this was now possible. I decided to go ahead and load 3 $100 GCs I had laying around. That worked fine. Then I went to 1 of my Ireland reservations (for June) that had ~$500+ left to pay (in May). I saw where you clicked to apply the gift cards and then I toggled each $100 gc and exited the screen.
This is where it was kind of confusing. It updated the final amount due correctly, but there was also a Button that seemed like I should click to Apply (I wish I had a screen shot). Anyway, I clicked it and it showed "The remaining balance of $237 will be processed on May 26, 2023" with a complete button (not sure 100% of the buttons labels on all this, but something like that). As soon as I hit "complete" (or whatever), my applewatch had a notification that $237 was going to be processed to my Cap1 VentureX. The reservation does reflect that the reservation is now completely paid, so it's not the end of the world, but the behavior and what it said on the screen was not consistent.
So, ymmv, but wanted to share. I'm not sure if I could have left the screen where it looked like it applied the GCs or not. I didn't think toggling the thing next to each GC would have actually applied it since you could go back and forth. Anyway -- glad the GCs were applied, but it was definitely clunky.