Real, Juve and Barca are not pushing for this to level the playing field, or because UEFA is corrupt. Any more than cockroaches come out at night because they’re just trying to clean up left-over food.
They have been knocked off their perch by PSG, City, etc. who now control UEFA. And the EPL is streets ahead of their respective leagues, where many of the clubs are just trying to stave off bankruptcy.
“We wouldn't be leaving the EPL, would we”. Nope. But it doesn’t take the seeing stones of the Palantiri to see that the ESL, expanded into a proper league competition, would basically compete with the EPL for TV money and audience.
Rather than fall for the schemes of Perez, Agnelli et al, the EPL should take this opportunity to invite Rangers, Celtic, and Ajax to join the EPL. With subsidy/compensation arrangements to these other leagues, and promotion to the EPL for their league winners.