I believe the government called this scaremongering at one point.
www.theguardian.com/politics/2020/sep/23/truck-queues-could-be-7000-long-when-brexit-transition-ends-ministers-warn
www.theguardian.com/politics/2020/sep/23/truck-queues-could-be-7000-long-when-brexit-transition-ends-ministers-warn