Honestly, if we’re talking about mostly or completely surface blasts, and not atmospheric detonations, that might be what saves the planet.
Nuclear winter is very much a thing by how the thrown-up dust reflects most incoming light, and with most detonations being in cities, the kicked-up dust would contain plenty of iron… which is the major limiting factor of phytoplankton, the largest single converter of CO2 to O2. All it has to do is fall out of the atmosphere and into the oceans during the spring to summer. So we need a late winter or early spring nuclear war.
When you really look at it, only type 1 & 2 plastics are recycled with any real frequency (80+%). And even then, there is a subset of plastics marked with those two types which cannot be easily recycled.
Meanwhile, while types 3 through 7 are “recyclable”, in reality these are actually recycled in the very low single-digit percentages, or not at all. Most of the rest are incinerated or shipped off to third-world countries for “processing”.
As such, most any plastic that are not marked type 1 or 2 should be binned with the trash, especially if said trash is going to be effectively and correctly entombed in a landfill.
Not only does it contain said plastics so they don’t contaminate the wider environment (especially if the landfill is correctly designed with a liner), but it also puts them all in one spot for when technology unlocks effective ways of recycling these types - there are emerging companies that foresee a time when we will “mine” our landfills for resources, and our best current strategy is to contain and concentrate our waste in as convenient a manner as possible.