Is it normal that the PhD research proposal of a candidate be completely written by his/her supervisor without them being involved?
This is a regional practice more than a field-specific practice in my experience. It seemed to me that countries like France that are very strict on the 3-year limit for PhD students tend to have the advisor work out the research topic in advance so as not to waste valuable research time, whereas in countries like the US or Germany, where there are only practical/financial limits on the time you are allowed to be a PhD student, the advisor will more often let the candidate look around a bit at the beginning and formulate the topic themselves.

Another aspect is grant money: if your position is part of a specific project (especially if funded on one of the big EU grants), you are bound to work on a specific question anyway, so there is not really a point in letting you paraphrase a topic that was already fixed well in advance of looking for a candidate.