this is the whole filter, I am following these instructions https://tiddlywiki.com/static/Customising%2520Tiddler%2520File%2520Naming.html
Sorry, I got it working with
[has[created]get[created]] [get[title]lowercase[]split[ ]join[_]] +[join[_]] right after making this post 
(source https://groups.google.com/g/tiddlywiki/c/a-EhnBSVUL4/m/reY8DFB9EwAJ)
[split[ ]join[_]addprefix{!!created}] didn’t work
but one question remains, it is renaming some special files: 20230526083557707_$_, is there a way to just filter my files?