I found the article that you quoted from:
The Big 12 might benefit in the short- and long-term if UT and OU leave early for the SEC
www.cbssports.com
That article does not say one way or another that the media contract under which Cincy, BYU, UCF and Houston entered the Big 12 does not give G5 schools pro rata. (In fact, the prior media contract DID give G5 schools pro rata). It says that the Big 12 didn't ask for a pro rata share.
"The legacy Big 12 programs shared money from their current distributions knowing Fox and ESPN
likely wouldn't pay equal value for the four new members. Those schools didn't bring pro rata (equal) value to the existing deal.
League sources said the conference did not ask its partners for increased rights fees".
Note: I am not going to undertake a research project to find the details of the Big 12 media contract for those years. I am going by what the article says.
The article DOES say that the prior media deal gave pro-rata for both P5 and G5 schools. "In 2016, the Big 12 considered exercising a clause in an old contract that would have compelled rightsholders to pay equal value
for any expansion. The Big 12 ultimately
decided not to expand at that time."
In an earlier post, you said "The Big 12 contract specifically states P5 will get the same additional money per team." I assume you are talking about the media contract that UConn would enter the Big 12 under, if invited. Do you have a link for this; I do not want to undertake a research project.