The whole thing isn’t going anywhere. First, get the often mentioned second opinion. And if you don’t have the money now, then do it in 1, 2, or 3 years. I know how it is, we’re renovating too. Three years ago, we first took care of the urgent things until the money ran out, and since then we’ve been doing the rest step by step, as the money allows. Depending on the craftsman’s advice, you can remove this insulation or leave it in place for now, but the plastering isn’t going anywhere. Or are there urgent follow-up trades connected to it? In the worst case, you’ll just have slightly higher heating costs for some time due to the missing or sloppy insulation.