Even if they had really shitty agreements I bet they'll see something substantial. Reports are saying it was a 5.3 billion purchase price. That's a lot of money for 400 employees.
Having 400 employees doesn't say much about how equity is distributed, though. E.g., (made up numbers, I know nothing about Plaid's comp specifically) if an employee gets 1 basis point over 4 years, that's 0.01% * $5.3 billion / 4 = $132,500, which combined with a startup salary might land you at around Google L4.
