Earlier quoted context omitted.
Old Dutch banks and their Belgian suckers, mostly. You can see a list on their website. I am not deep into this, but I heard multiple times that the choice of the pan-european payment system was largely political and technnically suboptimal. Old Europe pushed for the aging iDEAL against a much more advanced Blink, so Eastern European banks led by Poland left the consortium. In the end, iDEAL rebranded as Wero was dea…
Sounds more like you have some axe to grind https://epicompany.eu/members
Wikipedia gives an overview by year.
As for the axe, I have no personal interest.