There are options if you're willing to put in the work and run the risk of breaking things.

You can always not install QT or KDE packages and compile your desktop from source. It's a major pain in the ass but I did it for years. A side benefit is you can participate in testing and interact with KDE developers directly.

Another option is to go all FrankenUNIX and add neon sources to your apt cache. I've done similar but I don't recommend it.

Or you can just run unstable. Lots of people do. I did for a long time, and as long as you're willing to fix the package system occasionally it's not a bad experience. Certainly better than the two previous options.