Just for once, that is not the cause.
But the car manufacturers have largely only themselves to blame: they are so obsessed with just-in-time that keeping stock is alien to them. Then when Coronavirus hit and consumer spending initially nose-dived, they all miscalculated and cut back chip orders. Once they realised that their demand actually continues to be high (more people don't want to use public transport - pollution, congestion, and cities even more overrun by cards be dammed), they eventually ordered more chips but found themselves at the very back of the queue.
About the only parallels with Brexit is that nobody keeps any inventory so disrupting supply chains is very risky as UK2021+ is finding.