What does that mean? If the alias matches the file name, it’s just the file name, isn’t it?
This is how I understand it: Your observation above seems true if you set your links to shortest possible path (that’s the default). But in settings, I set my links to relative path, not shortest possible. So for instance [[directory/subdirectory/myfile|myfile]] appears as [[myfile]] in a linked note. If I change the filename from myfile to mynote, then it becomes [[directory/subdirectory/mynote|mynote]] and it now appears as [[mynote]] in a linked note.
If I deliberately set an alias on the original file that is different than the file name – for instance, on myfile I set an alias of “great file” – that alias will persist even if I rename myfile to mynote. So both before and after I rename the file, if I use the [[great file]] alias in a linked note it will persist.
I have not deliberately tested this yet, but that’s how I understand it.