I confirm a similar move in the area where I am living, adminstered by the German branch, quite some months ago already. All congregations elders were called to attend a special meeting where members of the branch comite explained the society could put the EUROs on the savings accounts of congregations to better use, if it was handed over the society. the society obviously can use it to help congregations in need with the money. Obviously if the congreagtion would need the money back, it will be returned to the congo, but without interest of course.
A resolution to that effect was put to the congregation, and sailed true with 98% of the votes of course, and some 8000 euros were transferred to the society.
So let us say a congregation put aside 5000 EUR every year, for maintenance works and so on. if it hands it to the society, no interest will be added to it, meaning after 10 years, instead of having put aside 50.000 and gained another 10.000 or so by interest, thereby compensating for inflation, there is only 50.000 that will be returned, and due to inflation, you can do way less with this amount of money. To make up for this, you can request the society for a loan, and guess what, you need to pay interest on that one.
I tried to explain that to my parents in law, but it did not ring a bell.