Signed PDF becomes Password Protected when renamed.

Hello, 

Mac OS 12.0.1, Preview app or Acrobat Reader. I used to be able to download documents from my Adobe Sign account, completed by clients, and rename them in order to save them into a folder. For a few weeks now whenever I rename a file it becomes protected with a password unknown to me. I could keep the filenames as downloaded but then I can't identify the files since they are the names of the templates + an incremented digit. Obviously it completely messes up my system. Why did it change, how can I change it back?

Asking help via chat (tried it x2)  was completely useless. They tried to convince me that I made the files password protected. One guy said that it will be bumped up "to the next level" and someone will call me the next day, yes, of course no one called me. 

So right now I have to physically print then scan the documents so I can save them under the name I want.  

I hope someone can suggest an option more friendly to the environment (and my time management).

Thanks.