This is from Adobe's site:
What does it mean when a question mark shows up on one of my folders?
The drive that contains the folder is not connected, the folder is not where Lightroom Classic expects it to be, or the folder name has been changed outside of Lightroom Classic.
In the Folders panel in the Library module, Right-click (Windows) or Control+click (macOS) the folder and choose Find Missing Folder.
Here is an in-depth instruction:
Thanks - I was able to do that but I have a ton of folders so it's taking a while. I just don't understand why it happened -m maybe the update?
Show us a screenshot and we might be able to figure out what happened. Most frequently on a Mac it's due to a change of drive name or capitalization in the drive name.