It could be lots of things. A manipulated vocal sample, a synth, a combination, a tweaked sound from plastic scraping together, or actually might be a whale...
The “seagulls” on the Beatles “Tomorrow Never Knows” is a sped-up tape-loop of laughing. I made some otherworldly sounds by doing the opposite (slowing down actual seagulls and mixing that with slowed down bubbles).
Experiment, and see how close you can get, if you can’t find a clean sample to snatch somewhere.
GJ