Do you have sources on them looking at transaction data please? That is clearly not necessary for processing the payment.

Edit: Found an article in German - https://www.sueddeutsche.de/geld/zahlung-per-sofortueberweis...

They claim they need to do this to make sure there is sufficient money in the account, even with transactions that might not be reflected in the balance, and they also check for other "Sofortüberweisungen" to detect fraud. Makes sense in a way but still quite shady. If there wasn't enough money in my account, or other transfers pending would my bank even allow their transfer?