Hidden links? How to get rid of?

Welcome.
The attached file contains probably some hidden links that appear only in August when we do even one "normal" link to another file. I tried with a macro that shows all of the links it contains the file, but it still does not show me the problem. I also attach screenshots that show an attempt to connect to external files (hidden links). I do not know how to remove them. Has anyone an idea what it could be and how to get rid of?

When you open the excel file, press update, after a long pause jump out messages about trying to connect to an external file. What is it and how to remove?

Thanks in advance...