We actually didn't have to provide any proof to the VR Bank either. We also had an EC card for the construction account. We built in 2020 and recently had to send 5-6 pictures, that was it. We currently still have money sitting in the construction account. When asked what we should do with it, we were told it was up to us. We also didn't have to provide any more proof because the construction was completed...
But we also had an offer from another bank (I think it was ING), where every disbursement amount had to be documented with a corresponding "invoice".