OK now I need to go down the rabbit hole of why other mammals don't get the bends. Here goes my evening.
Isn’t a key component of the bends breathing mixed gases while underwater? Similar to free-diving humans, other mammals are much less susceptible to the bends than human scuba divers. Possibly their innate behavior minimizes the risks further — like slowing their ascent as they get close to the surface?
Its not only the mixture, its also the pressure at which those gases are coming into your bloodstream. If you breathe compressed air you get the bends. As freediver you don't have much in terms of volume of compressed air, same for animals of course.