In Part 5 of "Super Mario Bros Adventures" from the May 1992 issue of Nintendo Power, Princess Peach (still called Princess Toadstool in the US) had just escaped Bowser's Caster with a flying cape, and she was gliding to safety when Mario zooms past her on a Bullet Bill.
She loses control of her glide and crashes to the ground, getting knocked out immediately.
There are exactly two panels of her unconscious in the whole issue, and she wakes up in Issue 6 in Luigi's clothes, as he swapped outfits with her.
Here is a link to the issue:
Source: https://www.superluigibros.com/super-mario-bros-adventure-comics-issue-5