Kleopatra disables the use of the clipboard for entering passphrases. This MAY remove some vulnerabilities in some situations, but it also discourages strong paraphrases: passwords that are long, use upper and lower case and punctuation. Is also discourages the use of password-safes which generate long, hard-to-type passwords. Let the user at least temporarily enable the clipboard, so un-typeable passwords may be used. Reproducible: Always
This is not a Kleopatra issue - it's a pinentry feature request which is planed for the next release.