No doubt this "flake problem" enters the process with the stabilizing bath, the filtered stabilizer left no "flakes" on this Ektar film after stabilizing and drying, but after filtering the bath the filter paper contained a lot of these glimmering flakes! And these flakes are not only related to the Ektar film. I have now successively developed 3 rolls, 120, of Fuji Reala, each time the film was hanged to dry before stabilizing and showing no trace of these flakes, before stabilizing. By filtering the stabilizer after each film I managed to avoid any problem to the stabilized film, but "flakes" no doubt was visible in the filter paper ... but less of them after each processed film (well, on film # 2 that was stabilized without having filtered the bath after #1 did show one piece of flake (!) that at least I hadn't discovered on the dry film before stabilizing it!).
Last time I developed 1 Reala and 1 Ektar and stabilized them immediately after washing in a newly filtered bath, and everything came out nice and clean; but after filtering the stabilizer bath I couldn't even find any trace of these flakes in the filter paper this time!! Perhaps my stabilizing bath is getting a little bit tired now, after all, it's film # 10 and 11 that this chemicals have been used to process.

I agree, Rudeofus, having tried to look into what the modern stabilizing bath is supposed to contain it's not easy to understand how these flakes are produced – but I can't come to any other conclusion than that they belong to the stabilizing bath, since no "flake problem" if I skip this last part of the process. Unfortunately, haven't yet heard anything from Tetenal (material and description have been sent to them) about some kind of explanation of this "flake" phenomenon: is it this particular batch of chemistry or my water, or my bottles, or my ...???
Anyway, I seem to be able to handle the "flakes" by always using a newly filtered stabilizing bath.