I've seen posts (not here) based on also trying to measure a person's knowledge on politics for them to be apt to vote...
The problem with that arises from various questions from my PoV :
Who gets to decide if someone is knowledgeable enough to vote? How do we determine which skills and knowledge are essential for voting rights? Should a macroeconomics expert who knows nothing about medicine be allowed to vote? What about a doctor who doesn't understand macroeconomics? Is understanding a country's racial or gender civil rights movements more critical for voting, or is it more important to know the history of the government's structure? Who decides what matters most? If a right-leaning person creates the test, it might disenfranchise left-leaning individuals, and vice versa. The knowledge deemed important could vary greatly depending on who sets the criteria.
What about the moral implications for those considered too unknowledgeable or unintelligent to vote, who then suffer or are suppressed without a way to improve their situation through the system? For instance, if a group is denied the education needed to pass the test, yet can't pass the test to vote for better education, how can they change their societal position?