After I installed the system and all necessary programs around 5 months ago, system size grew approximately by 45Gb from the initial 25Gb. I clean package cache and keep only 1 version of packages, current package cache is around 2Gb. I did not install any new programs during this period. I update the system every week. I clean journal with the command
Problem solved. I deleted files by selecting them and pressing DEL button. It turns out, this did not delete them, but placed in the “Trash” folder. I emptied the trash folder and reclaimed the lost 45 Gb. Thanks all.