As the Mach-E module section detail above illustrates, the Mach-E’s module architecture apparently contains a significant thermal design weakness – the plastic carrier bottoms. They block direct cell-to-plate heat conduction – the primary thermal path used in most other manufacturers’ current-generation pouch-cell-based packs. The only thermal path is through a long, thin passive aluminum thermal fin. With two cells heating it, this is too much heat for the skinny fin to efficiently conduct down to the cooling plate. It is literally a narrow thermal bottleneck.
For the Mach-E, high accelerations rates can exceed temperature requirements, causing the vehicle to reduce its power available. Probably the same for the Bolt EVs too (see EV Throttle Bottleneck Scorecard graphic at the linked article). These thermal issues might be why the maximum charge rate, which is just 55 KW for the Bolt EV while some EVs are now charge-able, in part, at 125 KW and higher.
Related: LG Energy batteries were also recalled, not just for the Bolt EV cars, but also for their home-based battery packs used for solar PV systems. They too had a defect that could cause them to catch fire.