I saw this topic amongst the two new updates on the French version, but I can’t seem to find it for any of the players – is there another specific place where I can view this?

Marketing
Your players now have followers across all their social media platforms, depending on their level, age, nationality and performance. Players also have an affinity with your supporters. These two criteria determine the players’ marketing potential. This marketing potential can be used to sell personalised shirts.

I suppose it will be visible in a window in the Workshop

You can check the number of followers each player has on their profile.

First, you need to unlock the workshop in question

Is it the same when it comes to rapport with the supporters?