If Vader refers to the carbon freezing tech as crude, then the tech must be from the past. The carbon freezing from this trailer is probably a more modern variant, safe for bounty hunters.
“Crude” does not equal “old”. It simply means it’s in a rough, not refined state. Like my cheap analogue watch from Walmart is a crude timepiece compared to the more sophisticated and high tech apple watch. Heck, maybe the Bespin facility was pieced together with parts salvaged from a scrapyard?
I agree with the sentiment that I prefer the idea of carbon freezing to be a unique thing done in ESB. However, I don’t have a real issue with it being used elsewhere in Star Wars from a technical, writing, or “plot hole” point of view. There’s nothing in ESB that actually indicates this is a unique idea that’s never been tried before. I agree with others that the “crude” comment refers to the poor state of the equipment and the question of Luke or Han’s survival comes from this poor quality, not necessarily that it’s a new process. We could even suppose that maybe carbon freezing living beings has been tried before but the success rate is low.
Also, this show takes place after ROTJ and you can bet that Captain Solo’s frozen form made a splash with the denizens of Jabba’s Palace. I’m sure word got around! Maybe there’s been a wave of carbon freezing going viral around the galaxy after that?