When I copied FF 85.0.2 to another computer, it lost its settings AND its add-ons. I had to do them all over again.
Assuming it was keeping them in Windows 7, I searched C: for Firefox. I got these on the source computer but they could be from past Portable Firefoxes:
The target computer isn't available right now.
Of course everything is supposed to stay in the Portable Firefox folder, so it's pretty serious.