Thank you! Using a Hex Editor solved the problem.
I installed a Hex Editor Extension for Visual Studio Code.
It has a Hex Side and a “normal” side.
I used the normal side to change the Name from UserConstructionScript to UserConstructionBLAHHH.
What I did then was to add it back, before starting the editor.
Earlier, I would always remove the blueprint file, start the Unreal Engine Editor, and add the file back by going the the folder using the default Windows Explorer. It would only appear in the editor, if I hadn’t changed UserConstructionScript. Otherwise it would throw that error mentioned above.
So, thank you Chatouille for the solution. Also thanks to Quetzalcodename for helping.