That sounds so dumb that I have to question if there’s some deeper reason, because otherwise that suggests certain things about the intelligence of Swiss regulators.

I couldn't find anything specifically swiss, but modern passivehaus standards recommend a combination of recirculating cooker hoods, that filter the big stuff like fat, and then combined with a whole house ventilation system that actively recirculates the whole house air, exchanging internal and external air.

These usually pull from the kitchen area (and bathrooms) to create a directional flow of fresh air through the house.

The extra cooker specific filter prevents the main filter getting clogged with fat. Previously people tried systems with a way to bypass the filters when the cooker hood was on.

This kind of system doesn’t really make sense. How could you ever filter out obnoxious smells like overly spicy chilli, or Indian curry, or oily stir fry, burned foods, etc…?

Can’t imagine anyone would want that to be ‘recirculated’.