Welcome aboard if you are using Buster - there is an issue with dpkg
Possible answer as used in Refracta eg. dpkg-reconfigure tzdata.
Quote:"darry1966: The problem is not with dpkg. The behavior of su changed when they moved it to a different source package. I've found the easiest way to restore the old behavior is to put ALWAYS_SET_PATH yes in /etc/default/su. (create the file if it doesn't exist)"
Try running dpkg-reconfigure tzdata from a root terminal this is an su problem may be fine with sudo. I haven't tested sudo as I don't use it.
I am personally very disappointed that this was allowed to be released in Buster - it caused hours of fustration as it affects dpkg -i and Gdebi-gtk. If your reading this and you are the su maintainer please fix.