Don’t Convert to R134a

Winchester_Black said
I just have one question. Do you ever plan to buy a refrigerator made after 2022?

Yup. I'm WFH today, at the kitchen table, and there's such a fridge about 10 feet away from me. Its charge is 60g (2.12 oz) of R600a.

Winchester_Black said
I’m only asking because r600 and r290 are propane and butane based refrigerants.

It's R600a (isobutane) and R290a (isopropane), number one. Number two, fridges are not motor vehicles. The operating conditions are hugely different, and so are the safety factors and risks. There are plenty of refrigerants approved for use in certain applications and not in others, for that exact reason.

Winchester_Black said
these are used in applications where open flame burners and vats of boiling oil are commonly placed in close proximity to them.

…in well-ventilated spaces much bigger than the passenger compartment of a car. This is a fine example of what "the operating conditions are hugely different, and so are the safety factors and risks" means.

Also, boiling oil—by itself—doesn't start fires.