Have they? I've seen this repeated a few times but all the various articles[1][2] I can find that say anything about this are saying that the growth rate slowed slightly, probably due to interest rate rises, but not that sales have dipped or even plateaued overall.
The main decreases seem to be driven by specific models declining[3] but otherwise the industry is healthy.
[1]: https://www.energy.gov/eere/vehicles/articles/fotw-1327-janu...
[2]: https://www.bloomberg.com/news/articles/2024-02-09/tesla-rak...
[3]: https://www.carscoops.com/2024/02/fords-ev-sales-drop-11-whi...