People keep repeating this like it’s fact, without ever having read the law. The original golden visa law clearly incorporated a bulletproof guarantee of access to the citizenship application process after 5 years. I believe it was @cj807 who did the research and dug up the details.
In the trailing months of the Costa government, when they were threatening to abolish the GV program, the EU smacked them for planning to violate the legal principle of legitimate expectations.
There are many worries and inconveniences about the program, but I don’t lose sleep about the citizenship requirements changing in mid-stream. I’m confident that the original GV law, which was in force when I applied, has my interests covered.