In this screenie you can see there’s a Collection Instance (?), but it cannot be opened. (it contains the lettering shown.)
There are multiple Scenes within this blend file, and most likely it is from one of these other Scenes (as it’s not apparently in this one given the Outliner).
How can I find where this is coming from?
EDIT: literally can’t find the lettering mesh data, so I cleaned up and uploaded the whole file. Voila:
Mystery Collection.blend (1.2 MB)