Am I doing something wrong?

[jellykrabbypatty]

I understood the question, I think. I have such files also grouped in different folders.
But I don't get it why JF should switch between different versions of the same movie, depending on the client watching it.

Since Jellyfin does a very efficient transcoding just keep the "best quality" of a file and JF manage the client capabilities automaticlly by transcoding the file in the required format.
I think the wrong way here is, putting lots of different encodings of the same file in this common library. There is no need to do so. It's simply wasted storage space.

So I think the issue is trying to adapt an old concept to JF, without the need to do so.

Ok, I think I get it. He wants JF to detect the client's specifications and choose between two different encodes (1080 or 4K) rather than transcoding one of them.

That's actually a good question. I'm not sure if that's something it can do or not. I would be inclined to say no based on what the person above said. I'm not sure what goes into transcoding a 4K movie down to 1080p and if there is a loss of quality. I know some 4K encodes look worse than a 1080p one if it's not on a 4K HDR TV. But again, my transcoding knowledge is limited.

If this is a thing you can do, you probably have to put them in the same folder and follow very specific naming conventions. Or just put them both in the same library and edit the metadata name with a custom 4K tag or something.