I should note that the redirector fix may be confusing on Unreal 5. More specifically, the command is now called Update Redirector References (but is otherwise located in the same place as in Unreal 4). That being said, however, it didn’t help in my case.
The good news, however, is that the affected materials were from a Fab purchase, so it was as easy a fix as to simply create a duplicate project, migrate the impacted assets over to replace the borked data and put everything back as it was before everything went to s— on me.
TL/DR: If all else fails, make sure that you always have a backup copy to fall back on.