Canon patented (via An Image on a Sensor) a series of lens designs ranging from 70mm to 100mm, all of which hew to a sweet spot aperture range between f/1.8 and f/2. Typically primes of this range have been small, non-L-class affairs, but these designs have a larger-than-average number of lens elements and groups, indicating they may be something more than merely fleshing out the lens lineup with cheap (well, cheap for Canon) options.

Canon Pricing Theory: $100 per Lens Element

The patent claims indicate the specific problem addressed is balancing two design priorities of image quality and size. That may leave ease of manufacture and a lower price out of the list. As with many of the RF lens patents, the application was originally filed in the latter half of 2019.