In the (largely American-dominated) western anglosphere Polarization is on the rise because of a cultural conflict over the solutions to the problems of the next 50 or so years.
Namely: Climate change and climate migration.
The shrinking marginal utility of the average person.
Unequal outcomes between groups.
Adaption to rising challengers to American global military dominance.
It's not some irrational thing produced by consuming different flavours of news - it's a fundamental schism in group orientation between two largely incompatible approaches to future challenges (largely a fight between bottom-up designs that seek to minimize harm and middle-up designs that seek to maximize growth).
We can't just lay this at the feet of media companies and their intermediaries, that's far too naive.