I highly doubt there was five hours worth of material for Godzilla vs. Kong, but I also have no problem believing that they gutted hefty chunks of the film involving Monarch, Mark Russell, and his boss played by Lance Reddick, credited as Guillermin. Also, that five hours could also be extended or alternate takes of the same scenes. Sometimes in films, subplots or dialogue elements get re-arranged or placed elsewhere. Or dialogue gets reappropriated to other characters. Or characters ultimately arrive at the same destination by different methods. Case in point in 2008's Iron Man, the film has Tony going to Dubai and meeting Ghostface Killah in his deleted cameo, gets thrown into bed with a bunch of hot girls and leaves, which is how Iron Man gets into the Middle East to save Yinsen's village. When Tony returns, he's still wearing the armor in Dubai and Pepper finds wearing the battle damaged armor, and he tells Pepper to help him get out of there.
In the final cut of the movie, the continuity of that sequence is totally altered. Tony just flies to the Middle East on his own, and then when he returns, Pepper finds him with JARVIS trying to help him get out of it with the gantry. So that's an example of how you can have extra deleted footage that doesn't really fit the flow or continuity of a film's final edit.
FYI, you don't bring in an actor like Lance Reddick for a throwaway line and character like that for one scene. Like basically blink and you miss him.
Chances are they cut most of it to focus on Team Kong/Hollow Earth mission and had Madison with Bernie and Josh as the B-plot of the film. I can sort of understand that having more of the Hong Kong/Monarch people could've risked hurting the flow or pacing of the movie or made it too long, but whatever.
I don't think editing or pacing are Wingard's strongest attributes. Case in point, Death Note, which seriously rushes over and glosses over a lot to boil down what is a very dense, deliberately paced story in the manga.
Kong is his fated rival.