True. The dear guidelines, we ourselves have had to experience them during the financing.
It is a new development area, which is being developed and sold step by step. In BORIS NRW, our partial area is still listed as arable land at €5. One bank seriously applied this value, which of course totally ruined the loan valuation. Another applied the lowest value from the direct neighborhood. Others simply used the purchase price as the market value, and that also resulted in the best conditions.
One bank delegated the valuation to TÜV, which saw a value €2 per sqm higher than the purchase price. Wherever such things come from
Land reference values are determined by the appraisal committee. Some federal states publish this online. Bavaria also has a system (just google BORIS Bavaria), but if I see it correctly, it is chargeable.