Problems copying special letters

I am an Apple user and currently I'm using the latest version of Adobe Reader DC as well as the latest operating system Mac OS 11.4. I depend on extracting texts from PDF files in both French and German. So far, this has always worked perfectly. Recently, however, Adobe seems to have a problem with copying special symbols. Other Mac users in our company have the same issue (since about 2 weeks). Instead of a special symbol, only a space is inserted. What can we do? I have already contacted various computer scientists who have gone through everything. They told me all it seems to be a problem that comes along with the latest update from Adobe DC.