I listened to Gura slapping her thighs and noticed something unique. 

When she was panting into the mic, she was trying to mask the sound of her slipping down her pj's to slap her bare thighs. I know she's wearing pj's because the first time she tried to slap, the fabric was too soft and likely too thick to hear anything, she also explained that she'll wear pj bottoms sometimes.

So the second time, when she's pressured by Kronii and Bae, she goes all out and removes her pj's then slaps her bare thighs, BUT If you listen closely, she was hitting her inner thighs, which tells a lot. 

There's a difference between slapping your outer and inner thighs. When you slap your outer thighs, it has a flat pitched sound. Yet when you're slapping your inner thighs, it's a high pitched slap. 

So Gura was slapping her inner thighs, which means she was in her panties or none at all as she was hitting them. 

Also, Gura appeared to be sweaty since the slapping sounds are also slightly wet. She did explain that her apartment doesn't have central air conditioning and she could be ve slight anxiety which makes you sweat. 

So in conclusion, sweaty Gura removed her pj bottoms and was slapping her sweaty thighs while in her panties or bottomless. 

Just give a listen and you'll understand more