There's a lot of subjectivity when it comes to this, and a lot of players probably aren't that aggressive in negotiations. You can drive player deals lower by skewing more heavily on agent fees, or clinch the deal that way with comparable terms.
We need specific examples so while we can take a look at the players in the screenshots, if those transfers have already taken place it does limit what we may review in regards to it.
We welcome save game files where these are the case so that we can take a look into things further. That will allow us to investigate what is happening in these transfer deals. A guide on sharing saves is available here: https://community.sigames.com/bugtracker/instructions-and-notes/how-to-upload-files-to-us-r98/