SUMMARY
During packages upgrade from 18.04 to 19.12 some packages still hold libqca-qt5 dependency with old version 2.1.3. When manually upgraded to 2.3.0, automatically removed with installation kde apps 19.12 can be again installed i.e. korganizer, kmail, libzip4, okular and some others.

STEPS TO REPRODUCE
1. upgrade to kde apps 19.12
2. can be noticed some apps previously installed are missing,
3. upgrade libqca-qt5 w/ new 2.3 version,
4. possible to once again install apps from 19.12 repo apps

OBSERVED RESULT

after upgrde missing packages

EXPECTED RESULT

full upgrade to all install packages

Operating System: KDE neon 5.18
KDE Plasma Version: 5.18.2
KDE Frameworks Version: 5.67.0
Qt Version: 5.14.1
Kernel Version: 5.3.0-40-generic
OS Type: 64-bit
Processors: 4 × Intel® Core™ i7-4600U CPU @ 2.10GHz
Memory: 15,1 GiB

ADDITIONAL INFORMATION