This is a change in behavior that happened with 3.0 previously Kleopatra would create a decrypted temporary file during decryption in the output directory that was selected beforehand.
With 3.0 Kleopatra immediately starts decryption to the user temporary directory and the user can select the output directory during the decryption process. This does not work for some usecases especially if network drives are used.
Kleopatra should have an Option to create the decrypted temorary file in the same directory as the encrypted file.
This issue was moved out of T3598:
(2.) Decrypting the file via Kleopatra speeds the process up significantly, but the decrypted file is temporarily generated in %temp%, i.e. the temporary directory of the respective user. Thereafter the decrpyted file is by default copied to the folder in which the encrypted file is stored. This is fine as long as the system disk is sufficiently large to generate the decrypted file. But as M.2 SSDs are now becoming increasingly popular (e.g. my laptop), the space may be limited such, as that this operation fails as the %temp% directory runs out of space. My laptop, for instance, features a 256gb M.2 system disk and my CAD and FEA S/W allready consume a considerable part of the disk's capacity. As this is a CAE certified workstation notebook, replacing the SSD with a bigger one (for a furtune btw) just for the sole purpose of decrypting large files isn't an attactive option.