https://www.freon.com/en/industries/refrigeration/residential-refrigeration

R134 was the “safe” refrigerant to replace R-12 because R12 is 11000x more potent of a ghg than co2

There are some new refrigeration units that use R600 but the vast majority of refrigerators are still R134

R600 being a highly flammable gas (it’s butane) has slowed its rollout a lot. Hence why a solid state non volatile refrigerant is still a cool development