Can we 'turn off' new OneDrive shortcut naming convention due to causing long filename backup fail

OneDrive does not allow you to customise the default naming format for shortcuts. The system applies a predefined structure that usually includes the folder name along with its source, such as a SharePoint site or the owner’s name. You can rename shortcuts manually after they are created, but there is no option to set an automatic default format.

Possibly an automation / script of some sort to manually change it will be the best of your bad options
Sorry that I am kind of just telling you what you already seem to have found.