Here is one of the mechanics I listen to on YouTube because I used to repair cars for a living.
He says the new Freon to replace the 134a which is what currently goes into car AC systems has several disadvantages:
1) It’s flammable unlike the 134a. Which means in accidents it can cause a better chance of a person being blown to bits or burned up.
2) When it burns it creates very toxic fumes.
3) It will be so expensive to fix it will almost cost as much as a good used car
4) Your mechanic will have to buy all new equipment costing 10’s of thousands of dollars to service this type of AC that to make up for his loss he’ll have to charge so much more it will make your head spin.