I do not believe that this leads to more unrealistic financing. This was already somewhat curbed this year.
I just calculated for a married couple what earnings would be possible. With 2 x €40,000 gross annual income, you come to about €67,000 income. €40,000 gross annual income means about €2,200 net per person. Family net income would then be €4,400.
I must admit, when I read the salaries here in the forum, that is not all that unrealistic. Whether you can build a house with €4,400 and 3 children, I don’t know. I suspect that rather small families are the beneficiaries of this support.
Furthermore, a loophole could arise here if higher earners, for example, are on parental leave in that year and thus their income temporarily falls below €70,000 or if entrepreneurs shift their profits to other years.