For the safety of swimmers, we deliberately changed the shape of the glass and increased the amount of air in our mask, which complicates diving for a beginner, but does not interfere with experienced swimmer.
An experienced swimmer knows how to work with extra buoyancy or uses a Diving weighting system (https://en.wikipedia.org/wiki/Diving_weighting_system).
In an emergency, a swimmer can easily unfasten a Diving weighting system and get out, performing all the necessary actions to preserve life and health. For example, 33 feet is the depth of the free diving of an ordinary trained swimmer. Without a Diving weighting system and in fins from this depth to the surface, it takes 5-10 seconds of relaxed movements to float.
That is why the required certificate OW or higher / other certificate - when you get a certificate, the swimmer gets the necessary knowledge and skills.