Rubber particles from tires are one of the main sources of microplastics.
On the other hand, carbon emissions are known to cause global warming which will literally be the end of the world if we don't fix it fast. From what I've read it may already be too late, we may already be on course for runaway climate change that we may not be able to fix.
To me that's a much more pressing matter.
Poisoning the oceans does not seem like a good strategy for the human race.
It's definitely an issue with ICE and EVs, but is often brought up in EV discussions as people get the impression that EVs are "pollution free" due to their lack of exhaust emissions. Also, EVs tend to produce more tyre dust due to their slightly heavier weight and increased torque.
Incidentally, a small Chinese study found 6PPD and 6PPDQ in human urine in low concentrations. We don't currently know what health effects, if any that may have.