R12 vs 134a

yeah I went to a few of those but 1. those were like what 25 years ago? "CRS" happening.
\and 2. Since then the places I have worked are places that didn't offer AC to their customers. I now work at a place where I'm doing more AC work again but R12 never even comes up.... I see a few that specify this 1234 YF but I haven't worked on one of those systems yet.
Will retrofits begin to skip 134 and start going to this crap? I know nothing about this newest freon.