Almost all of them use either HFC or The HCFC refrigerants. HCFCs are being phased out but they still damage the ozone layer. You can’t even buy a conventional split AC system in North America that uses HFO or natural refrigerants yet. Some smaller window units and refrigerators use natural refrigerants like isobutane and some industrial or commercial chillers use ammonia or CO2, but residential air conditioners are pretty much R410a.