In a .jpg file processed in Photoshop after transfer from an iPhone, the name of software was not changed from (iOS) 10.2 to Photoshop. Looking at the front end of the file with a text editor I see "Photoshop 3.0" as in the attached.
It would be handy to have exiftool pick that up as the last-used software.
I believe that is the start of the Photoshop chunk (https://exiftool.org/TagNames/Photoshop.html) in a jpeg, not the name of the last program to modify it. You'll should find the same thing in any file that has a Photoshop chunk, which by definition will include any file with IPTC data (indicated by the IPTC header 8BIM in your file). Try saving IPTC data with any other program, such as Irfanview or even exiftool. You should see the same thing.
Thanks. This and your previous posts on IPTC are really helpful. I especially appreciate your mentioning '8BIM'