Let's take as an example Poland, since it receives the most amount of money out of all members.

"The structural funds are for making weak regions more competitive. And a large part of every euro the EU gives Poland comes back to Germany. The Poles use the money to place orders with the German construction industry, to buy German machines and German trucks. So net contributors such as Germany should be interested in the structural funds. From an economic perspective, Germany isn’t a net contributor but a net recipient." - Günther Oettinger, EU Commissioner for Budget and Human Resources: https://global.handelsblatt.com/politics/oettinger-germany-may-have-to-pay-more-to-e-u-714934

Poland gets money from EU and then spends it plus even more of their own money on products and services offered by German companies, therefore Poland is being drained by Germany out of money, while making it look at first glance as if Poland was doing that to Germany. That's smart. Germany has a slave that doesn't even realize it - not only that - they think they outsmarted Germany.

The net winner in EU is Germany - https://www.auswaertiges-amt.de/en/newsroom/news/170322-bm-faz/288672
https://www.bbc.com/news/uk-politics-48256318