Time fixed it for both my kids. They got older and were more content.
My baby started crying every time she went in the car seat from about 6 months by the time she got to 7.5 she just went back to not minding it! Hopefully your baby will grow out of this too x
i’ve seen a lot of people have like a sensory toy attached to the seat opposite, like a fish and ocean one to look at to keep them occupied, could try that x