Lmao. I downloaded and thought i'd see for myself and it's real. Looked for all occurances of 'bubba' in all the docs:

/Epstein Estate Documents - Seventh Production$ grep -PiHnr ./ -e 'bubba'

./TEXT/001/HOUSE_OVERSIGHT_030716.txt:6:Ask him if Putin has the photos of Trump blowing Bubba?

./TEXT/001/HOUSE_OVERSIGHT_015032.txt:698:And remember that awful piece of gossip—the one Lucianne Goldberg initiated in order to get attention from the press for her—that I kept a blue dress stained with Clinton’s dried ejaculation as a souvenir? Well, Jonathan Brandmeier on KLSX invited listeners to call in and suggest euphemisms for presidential semen. My favorite was “Bubba butter.” Apparently, my role is to serve as a vehicle for the destruction of taboos.

./TEXT/001/HOUSE_OVERSIGHT_022673.txt:73:figure in the Western world); dissections of handwritten flight logs for the financier's private 727 aircraft that frequently capture Bubba

./TEXT/001/HOUSE_OVERSIGHT_022624.txt:212:Bubba Clinton is only the first to be exposed.

./TEXT/001/HOUSE_OVERSIGHT_022624.txt:702:Good thing it was on here for a moment or two, because once the powers that be get their paws on this, Bubba,

./TEXT/001/HOUSE_OVERSIGHT_022624.txt:704:By the time 2016 rolls around, Hillary and the co-president (Bubba) will be scrubbed squeaky clean and she'll

./TEXT/001/HOUSE_OVERSIGHT_030719.txt:18:Ask him if Putin has the photos of Trump blowing Bubba?

./TEXT/001/HOUSE_OVERSIGHT_022684.txt:78:capture Bubba at 30,000 feet; and extensive allegations from a woman, Virginia Roberts, who claims she was Epstein's sex slave as

I went to check that second occurance of 'bubba' to see if it's referring to the same person:

/Epstein Estate Documents - Seventh Production$ cat ./TEXT/001/HOUSE_OVERSIGHT_015032.txt | grep -i 'bubba'

Here's the result with some extra surrounding text for context as to where it comes from:

The Autobiography of Monica Lewinsky

The following is an exclusive excerpt from an autobiography-in-progressy by Monica Lewinsky, titled Going Down in History. The manuscript was leaked to The Realist by, of course, a reliable source.

Back home in Brentwood, I’ve been listening to talk radio a lot. Ronn Owens on KABC had listeners phone in with nothing but jokes about me for a solid hour. First he warned the audience that if they were easily offended, they should tune out. I have never felt so objectified in my life, and yet, at the same time, I found the program quite riveting.

The best call came from a nine-year-old who said, “Bill Clinton violated the Eleventh Commandment: Thou shalt not put thy rod in thy staff.” The worst call came from a man who asked, “What do the Titanic and Monica Lewinsky have in common?” The answer was, “They both have dead seamen (semen) floating in the hull.”

And remember that awful piece of gossip—the one Lucianne Goldberg initiated in order to get attention from the press for her—that I kept a blue dress stained with Clinton’s dried ejaculation as a souvenir? Well, Jonathan Brandmeier on KLSX invited listeners to call in and suggest euphemisms for presidential semen. My favorite was “Bubba butter.” Apparently, my role is to serve as a vehicle for the destruction of taboos.

Emphasis mine.

Jesus christ lol I can't believe it's real, Bubba really is Bill Clinton.

Of course we don't know the context for that convo from Mark (Jeffrey's brother), he could've been making a joke like alluding to finding compromising materials on Trump or something, but he could be implying that this is something that actually happened too.