Yoimiya's blazing arrows snapshot the damage bonus from her skill.
Although Yoimiya's skill ends when she swaps off field, her blazing arrow damage remains the same whether you swap off before it hits an enemy or stay on field.
In this video, you can see that Yoimiya's N1 did the same damage when I swapped and when I didn't.
We can show that Yoimiya's skill ends as soon as you swap off because blazing arrows that hit after you swap off cannot activate her A1 passive.
In this video, Yoimiya's Pyro DMG Bonus didn't increase, even though her infused N1 hit, because she was off field.
Better understanding of snapshotting - Even though Yoimiya's normal damage bonus from her skill is multiplicative and doesn't show up in her "Character Details" page, her arrows still snapshot it.