Make sure you have the following packages installed:
erlangen:~ # zypper se --match-exact -is akonadi-mime grantleetheme-lang kcalutils-lang kitinerary ksmtp libopenssl1_1 librevenge-stream-0_0-0 libXfontcache1 pimcommon-lang
Loading repository data...
Reading installed packages...
S | Name | Type | Version | Arch | Repository
---+-------------------------+---------+-------------+--------+-----------------------
i+ | akonadi-mime | package | 23.04.0-1.1 | x86_64 | Haupt-Repository (OSS)
i+ | grantleetheme-lang | package | 23.04.0-1.1 | noarch | Haupt-Repository (OSS)
i+ | kcalutils-lang | package | 23.04.0-1.1 | noarch | Haupt-Repository (OSS)
i+ | kitinerary | package | 23.04.0-1.1 | x86_64 | Haupt-Repository (OSS)
i+ | ksmtp | package | 23.04.0-1.1 | x86_64 | Haupt-Repository (OSS)
i+ | libopenssl1_1 | package | 1.1.1t-3.1 | x86_64 | Haupt-Repository (OSS)
i+ | librevenge-stream-0_0-0 | package | 0.0.5-1.2 | x86_64 | Haupt-Repository (OSS)
i+ | libXfontcache1 | package | 1.0.5-13.1 | x86_64 | Haupt-Repository (OSS)
i+ | pimcommon-lang | package | 23.04.0-1.1 | noarch | Haupt-Repository (OSS)
erlangen:~ #
Infamous host erlangen was affected by similar symptoms: Kmail no longer displays message body
Rolling back and forward again fixed the issue with the puzzling side effect of the above packages being now flagged as user installed. Checking zypper logs and journal showed that no user install was performed.