https://files.catbox.moe/j4quud.mp4>Feres Sauna *bae laughing*>Hey Sauna, Hey nunei>Haelz Baekos>someone does something in real life>*Someone laughs in a suspicious way, then bae cracks up*>I'm so sorry I didnt mean it like that>Stop talking stop talking>Hail like the rainSo clearly something was done, I'd say that whoever laughed just before Bae was innocent and whoever didn't laugh was the one who did this mysterious action. The laugh before Bae's definitely sounded like the one you do when someone says something extremely racist out of the blue. Fauna demanding that she stop talking supports that something "yabai" was done. Mumei saying hail like the rain suggests that "hail" was the bad part.
My theory is that after Fauna said Hails Bakos Mumei or Fauna performed a roman salute and the other one laughed in such disbelief followed by Bae really thinking it was funny and reassuring us she "didnt mean it like that". Due to her association with known anti-semite Mori Calliope I don't believe it however Fauna or Mumei may have just been doing it as a joke.