Tumbleweed is not really a distribution for beginners or occasional users, because the large number of upgrades - some of which come several times a day - means that it requires a lot of maintenance.
I know that I’m about to be put down again here:
I have been using SuSE/OpenSUSE since the beginning of 1998, and therefore Tumbleweed since it was introduced. And I have done all upgrades with Yast since then. The few times I had problems were after upgrades with the “zypper dup” command. I have been using my PC for several hours a day since 1998.
In addition, the “zypper dup” command has been modified under OpenSUSE anyway and does not run a “real” “zypper dup”.
Incidentally, I also upgraded from Plasma5 to Plasma6 initially under Plasma5 using Yast. This did not lead to the installation process crashing (unlike all those who carried out the installation via zypper dup under the GUI), because Yast excluded all packages from the upgrade from the outset that would have led to the running system crashing and did so for users of the “zypper dup” command.
I have to admit that I don’t know which program you are using to display upgrades under Plasma. I suspect that it is Discover in conjunction with packagekit. Discover has never worked properly, years ago packagekit regularly paralyzed the computer with its search for upgrades after starting the GUI.
I therefore permanently blocked packagekit and Discover in Yast years ago.
Your criticism that the packages are not removed from the basic installation from the outset is correct.