No software updates since Plasma 6

  1. zypper dup will automatically downgrade package versions. Maintainers of xz had to jump through the whoops and provide the nonsensical package version 5.6.1.revertto5.4 exactly for such stubborn users who refuse to follow best practices and who would not get their packages reverted with zypper up or YaST otherwise. Downgrades are not uncommon in Tumbleweed.
  2. zypper dup is using more aggressive strategy to resolve dependency issues. Normal zypper up/YaST tries to keep installed packages where zypper dup would prefer to remove them if this resolves the conflict. Again, this is not uncommon that new software version changes its structure and dependencies.
  3. zypper dup will automatically remove historical packages marked for removal in the distribution metadata (contained in the package openSUSE-release). This may sometimes also have side effect of eliminating (or, better, preventing) dependency conflicts.