If there is a civil war in our time, I have to believe it will be between the densely populated blue urban areas and the red rural counties, likely with the "front lines" somewhere in the suburbs. At some point, it's possible the urban consumers will go too far and demand too much from the rural producers. Look at the by county election map for reference.
If the (likely blue) governors/legislators/etc. start/continue to (even more) tyrannically impose their will (draconian Covid restrictions as an example) upon the counties while allowing lawless chaos in the cities, there's a chance it will result in the reduction of food and consumables delivered to the cities. Exactly where do they think all that stuff comes from?
With shelves empty, restaurants closed and urban gas stations no longer supplied by truckers not willing to brave the lawless mobs, and because they are so dependent, desperation would set in rather quickly. As the supply in the cities quickly dries up, the zombie mobs would begin mulling outward in search of all the stuff no longer stocked at their burnt out Targets and corner stores.
First they start to pillage outward into the near suburbs and then the far suburbs. Each time running into people a little more prepared and a little better armed. The bloodshed would begin in earnest as people try to defend what they have. The local authorities and military could only hope to contain the chaos and provide what they could to the "starving" city dwellers. But they would be pushed to the brink when supplies run low and mobs demand more. Inept city/state/federal leadership would seal the fate of the desperate.
Once the "relief stations" are all sucked dry and destroyed and the authorities pushed out, the zombie horde would continue outward. By this time the full military, LE and even deputized civilians would be mobilized. Those that didn't abandon their posts to protect their own homes would be in daily conflict with the desperate, angry mobs (no longer receiving their entitlements). Gangs of zombies would push outward, looking for resources, pillaging until they run into better armed mobilized neighborhoods and towns, where they would be met with overwhelming defense.
This would likely happen similarly in many other places around the world, once word got out, the global economy crashed and panic set in. Then "help" would arrive in strategic places around the world. Whoever remained strongest would certainly provide "aid and support" through their military, and the conflict would grow over whatever is considered valuable.
None of this is remotely inevitable, but I would also caution that is is also way closer than it seems.