Well, appreciation / loss in value is just as unknown in advance as interest rates. Everything is possible, nothing is certain. Two years ago, hardly anyone would have expected 7% inflation and a war of aggression against Ukraine. This has nothing to do with "everyone knows better," as someone wrote further up, but simply with different personal attitudes toward risk. There are valid arguments for both variants, both are legitimate. Someone who is not willing to take an interest rate risk in the future fully hedges today and accepts additional costs for it. I wouldn't even say you only know after 10/15 years "whether it was worth it," because maybe it's already worth it in that the risk-averse person can sleep better at night knowing the worst case is known.
I believe that due to the new government and the shortage of materials, the supply of single-family homes will decrease. The construction industry will have a very hard time soon. Sure, it’s like religion when it comes to belief, but in my opinion, the likelihood of value increases is higher than that prices will plummet. We are talking about outskirts and not houses in big cities where the price is slowly reaching its peak (in my opinion). And if the value stagnates, then after 10 years you have paid off a financing sum x and the equity ratio increases.
If we assume the worst case, Russia could also drop a nuclear bomb on Berlin, then the value, even 50km away from Berlin, would fall to zero.
The future is clearly uncertain, so one can only work with assumptions/probabilities.