The supposed hypocrisy is that Amazon, a company, has a different view on mail-in voting than Jeff Bezos, a person.
While true, and while likely that Bezos could possibly change Amazon's stance on this, it shouldn't be surprising that a large company relying on low wages would take any stance to stop it. Amazon may consider unions to be an existential threat.
There's no story here, just like there's no story that many companies donate to Republicans despite having liberal founders/CEOs. Elon Musk famously donates to both parties, although one assumes he personally has a preference for one (or neither) of them.