Welp, apparently I needed that prefab! I have it in old versions – so turns out I can just drag and drop from another unity window to my current one. I do this by having two versions of unity on my computer, so I can have two projects open at the same time to check changes, etc. I’d rather they both be the most updated version of Unity – #todo – look into if I can just download it twice. Or if there’s a way to have multiple projects open without having two versions, cuz that seems silly.
So it turns out that prefab is on objects in the scene, and now instead of being named “1” and tagged “Onset”, they’re named Missing Prefab. How do I plug the prefab back in?
OOH even better. I took the whole set of objects from the scene in the old version (4 gameobjects nested under an empty gameobject, “Onsets”), made Onsets a prefab, and then moved Onsets into the prefabs in the new version. Then I put that prefab back into the scene, and voila! All happy again.
There were multiple other resources I glanced through, but didn’t feel like this was necessary to do through scripting. For future reference, here were some things that may or may not be helpful: