I am a male born in 1964 in USA.
My father is a male born in 1931 in USA.
My grandma was born in the UK in 1903.

I thought 4C is for citizenship through women. (My chain goes woman —> male —> male)

I thought 4L is the route for me because I had a consular registration requirement that was impossible due to gender discrimination. The Romein decision removed the consular registration requirement.

I wouldve been a British citizen if my grandma was recognized as citizen to pass down to my father, who I would then get citizenship via consular registration from.

I have been that the home office is trying to categorize some people as 4C instead of 4L to limit claims.

This clarification matters because I want to know if I’d get citizenship by descent (4C) or otherwise than by decent (4L)

You'll need to apply to be registered under Section 4L using Form ARD so you'll become a British citizen otherwise than by descent. See Example 13.