What is this "Legacy developer: hp" asking to change my extensions?

I just followed the directions of iZac100 in this earlier thread on this topic:: How clear "System Extension Blocked" mess… - Apple Community

Basically, I also no longer have an HP printer so I deleted all the HP extensions in the Library/Extensions folder. I then did a restart and this problem was gone.

I am having the same problem, several of these "Legacy developer: hp" attempting to load at startup, and being rejected as not authorized. I am wondering if it could be from HP Printer drivers that are no longer in use? They would get into the list of .kext extensions from a Time Machine backup being loaded to transfer to an new machine. Because the messages are all generic and listed several times, it is impossible to know what the extensions are attached to. However, in my case I did have an HP printer a long time ago attached to a previous machine. And this machine was built from a Time Machine backup of that old machine. If such is the case, I'm thinking to go into the Extensions folder and delete all of the .kext extensions associated with HP printers, and see if that corrects the issue. Any thoughts? My only reservation is that HP doesn't stand for Hewlett Packard, and it is something completely different.