The one with the pink hair just below Yukari is Aura from Frieren (some how still attached to the rest of her body
The dark-haired girl on the right toward the top is the main girl from Gushing Over Magical Girls (Mahou Shojo ni Akogarete), idk her name Edit: looked it up her name is Utena Hiiragi
It’s a potion that dissolves clothes. Frieren (the white-haired elf) intended to give it to their male party member for his birthday.