Yeah, I do get, that this is a reasonable easy enough thing to do

The first result I get from your link is a bash script, that wouldn’t do this stuff automatically.

So I would be interested where you got this extension installed and in what parts of the system it is actually working.

So does this work as well, wenn die rename a file in a shell?
Which I would find rather strange, tbh, but would be interested, how that is implemented

As extension of a file browser, I do get that this could be quite popular.

Could you just try that one case out?