Is the price increase for the general contractor after signing due to raw material shortages lawful?

and is it foreseeable that it will get better again in the future? You can say goodbye to the old prices anyway, they certainly won't come back ;)

So far, he has only hinted at it as a side note. The bigger problem he described was primarily about procurement and incidentally mentioned how we could then solve it financially since no one could have anticipated it. If you Google it, it seems that currently there really is a very tricky situation on the German market.

I don't understand that. I can reject any extra work, review amendments and refuse their payment until everything is verifiably submitted. You will be surprised what is possible. But only those who have learned how such things work know that.

I would have another suggestion. One can accept part of the additional costs, but never without consideration. For example, one would then negotiate and contractually fix a deadline guarantee and/or payment only after defect freedom.

and is it foreseeable that things will get better again in the future? One can say goodbye to the old prices anyway, they surely won't come back ;)