I don't really know, but I'm taking delivery tomorrow and using plaid (pay via the app). Today I clicked the button in the app to add an account, then selected my bank. It took me into my bank's app and the bank made it clear that it was not sharing my username/password with Plaid (or Tesla), and it was generating substitute account/routing numbers. So later when you go into your bank app, after you've paid for the car, you can disconnect Plaid/Tesla from having further access to your account information and they won't even know your real account number.
It said they can read balance as of the previous business day, and transactions (recent, including pending). So probably best to kick them out after you pay for the car. Especially after seeing the bit recently about Tesla getting sued for employees sharing people's videos, maybe data privacy needs a little work.
Anyway, after you go through that then the "add account" button changes to "Pay". I'm assuming I can just hit that button tomorrow after I inspect the car and decide to take delivery. I'll report back if it ends in disaster tomorrow