This should help you understand the venting or help me, I dont know which -
"A thermal management system is provided that minimizes the effects of thermal runaway within a battery pack. The system is comprised of a sealed battery pack enclosure configured to hold a plurality of batteries, where the battery pack enclosure is divided into a plurality of sealed battery pack compartments. The system also includes a plurality of battery venting assemblies, where at least one battery venting assembly is integrated into each of the sealed battery pack compartments, and where each of the battery venting assemblies includes an exhaust port integrated into an outer wall of the battery pack compartment and a valve, the valve being configured to seal the exhaust port under normal operating conditions and to unseal the exhaust port when at least one of the batteries within the battery pack compartment enters into thermal runaway."
https://xray.greyb.com/ev-battery/tesla-thermal-management-techniques-for-ev-batteries
I think this explains it better. Obviously it is a weak spot or Tesla themselves would not tell you to park your Tesla away from structures if submerged in salt water. I mean, it really doesnt need more explanation than that.
But here is an SAE story.
https://www.sae.org/news/2020/09/venting-for-ev-battery-packs