Because Tesla is a brand that relied entirely on the CEO for PR/Marketing.

And it's indisputable that Twitter is in serious trouble.

By Musk's own admission the company is worth less than half what he paid for it. Revenue has plummeted, toxicity is rampant, lawsuits are increasing and Twitter Blue has been a disaster that will likely be researched for years.

And so all of this chaos has dragged Musk's reputation down which in turn is affecting Tesla.