GPL has no requirements for author attribution which is contrary to the entire point of an MIT license.
That’s why I described it as joining the Borg. You release individualism and freely give it to the collective. That’s cool, and I get the ethos behind all that, but I don’t want to add any of those constraints to my code. I just don’t want credit for my work or the others to get lost. I don’t think it’s a hard ask.
Regardless, we ended up ultimately being a full replacement for the other project.
There is no section 15 or 16 in GPLv3, but I did find section 7 saying:
But that’s an optional thing that you must add onto the GPLv3 license. I’ll have to keep that in mind for the future.
That would explain why what I’ve read mentioned it’s not guaranteed in GPLv3 (when comparing to MIT). I’ll have to figure out what that notice would look like.