One way to measure the level of competition in a championship is to divide the points earned by the runner-up by the champion’s points. Expressed as a percentage, this quantity is between 0 and 100. Measured by it, ADAC Formula 4 was the most competitive championship in 2020, while Formula 1 was the least competitive.
Consider that FR Americas uses the same scoring system as F1, and its season also had 17 races. Lundqvist won 15 out of 17 (finishing P2 and P6 in the other two), and even that championship was closer than F1.