@@amy-295 I tried with Wriothelsey and other Cryo characters I have and no, they cannot do it. But when I tried with Ganyu, it worked. I think this can be done only with Ganyu.
You need to destroy the Contaminated Bacterial Mat (Floating Green in the pond) using the blue orb (Xenochromatic Fontemer Aberrant) near the pond. The details just open archive > tutorial [?]