The inhabitants of the submarine aren’t under pressure directly like scuba divers are, they’re at atmospheric pressure while inside which is why the pressure hull needs to be so strong to resist the hundreds of PSI outside - it’s the pressure difference that crushes things in this case. If they are rescued there’ll be no requirement to decompress slowly as their bodies were never under compression and at risk of the bends (when nitrogen bubbles form in your blood with often lethal results) to begin with.

The inhabitants of the Kursk during that submarine disaster were subjected to high pressure in their last hours but that was because the water slowly flooding their compartment compressed the air like a piston, this isn’t a concern for this submarine as it goes far deeper than the Kursk and the slightest fracture to the hull would kill them instantly in a violent implosion.