Since Tesla funds Dahn's research, they get the IP. This is just in the lab but those advancements are trickling, over time, to Tesla's battery making (and not just Tesla: every battery maker does research to make batteries cheaper and last longer).
Supposedly, first-gen Leafs were known to have pretty nasty degradation due to lack of sufficient cooling. Combined with an already short-range battery, and the belief that you'd need to replace the battery frequently was justified.
Key word: WAS
Of course, modern EVs, and basically all Teslas, have bigger batteries with better cooling, so it's no longer an issue. But the belief won't die, just like how people still make memes about Java being slow as if it's still 1998.
Here's the truth based on an observation: Tesla's battery capacity degrades 12% after 200k miles. Source: https://insideevs.com/news/664106/tesla-battery-capacity-deg...
200k miles is effectively the lifetime of a car. Average US person drives 10k miles so that's 20 years of driving.
Tesla's warranty "guarantee at least 70 percent retention of battery capacity over 8 years and 100,000 miles or more". Source: https://www.motortrend.com/features/tesla-battery-warranty/
And latest chemistries are even better. In 2020 Jeff Dahn (who leads battery research group in Canada funded by Tesla) published a paper about million mile battery. Source: https://www.electrochem.org/dahn-unveils-million-mile-batter...
Since Tesla funds Dahn's research, they get the IP. This is just in the lab but those advancements are trickling, over time, to Tesla's battery making (and not just Tesla: every battery maker does research to make batteries cheaper and last longer).