What does the red X icon mean?

[Killavolt]

I'm renaming some files that were already renamed by FileBot, and in the rename panel there are a number of files that have red circle X icons beside them, but the names are identical from what I can see.
There are others that have green arrows and most have no icon at all, even though the names are mostly all the same

[rednoah]

Screenshot? Context?

The green and red icons typically indicate that a file cannot be processed due to fundamental file system limitations, e.g. likely a file already exists at the target file path, and moving forward would require FileBot to overwrite that file.