I have run across this onomatopoeia twice now in music lyrics:
打上花火 by DAOKO × 米津玄師： 「パッと光って咲いた 花火を見てた」
GHOST by 星街すいせい： 「パッと弾けた感情に」
Having seen this occur twice now, I felt it was safe to assume that this is not merely a stylistic choice made by the lyricists. This was reinforced when I looked it up on Jisho, which lists the main spelling as パッと instead of パット or ぱっと.
From what I can remember, I have never seen another word spelled like this, with part of it being ひらがな and part of it being カタカナ. Or at the very least, if I have, this one feels particularly curious, since I have always figured that the small っ／ッ characters act as a fixed construct where they are modifiers of the following syllable's consonant; like they're attached. So, if anything, I would expect the word to be spelled ぱット or パっと, with the っ／ッ sharing the script of the succeeding character.
What's going on here? Why is it this way, or, how did it come to be this way?
Secondarily, are there any other words that share this characteristic?