I can't imagine that. If you buy your property at -x% of the market value, then the bank will only use this purchase price. When someone sells their house or land or both, it is appraised beforehand and not just based on the purchase price from back then. Especially land increases or decreases in value.
The bank looks at what the land is actually worth and not: how much was paid for it. It may also be that you paid too much (at least from the bank's perspective). Whether the bank actually uses this value at 100% is another matter. If the buyer or seller buys/sells the square meter at 100€, it can very well be that the bank sees it differently and only calculates with 90€/sqm. Because in case of doubt, they believe nothing more can be gained. So if you get the square meter for e.g. 80€, it can just as well be that the bank says: it is worth 90€ for you here.
We were given our land as a gift. No bank will now come up with the idea to say: value = 0. The local customary price per square meter is used as equity, end of story. Moreover, in our case, when it was still greenfield, the price per square meter was well under 10€, even at the time of purchase. Now it is 270€; trend rising. The city also bought an undeveloped part of the land from us last year for almost 200€/sqm (building land) and did not say: you were given this as a gift, so now you have to give it to us for free. That would be even more ridiculous.
A flawed comparison: You buy a stock for 5€, it rises in value to 6€ and you sell it, the buyer also does not say: but you only paid 5€ back then, you won’t get more from me now. On the other hand, if the stock falls to a value of 4€, no one is willing to pay the original 5€ just because it is on your old invoice...
So it is what it is worth, not what was once paid. However, the value should be realistic and not, like in the USA, far overvalued. Because if it is sold then, no buyer will be found (at least at that price). Then the bubble bursts :)
But that is just my experience. schubert79 seems to have had different ones. Or he didn't buy far cheaper, but everyone else simply bought too expensive :)