Its possible, if theres a full database dump that direct messages could also be leaked, which could be incredibly damaging. I'd guess that these would be in another storage medium however.

One wonders. Why are encrypted passwords stored in an external code repository?

I'll be curious as well once this makes it's way to haveibeenpwned. Requested for it to be deleted and forgotten few years back, wont be the first time an account of mine has been "deleted" to then miraculously be hacked or caught up in a leak

Kind of worrying considering my twitch is linked to my Amazon account, and all my banking credentials are linked to Amazon.

That's only a very narrow link though, isn't it? Just lets you claim Prime benefits, doesn't give access to Amazon purchasing or payment details or anything?

If it's any comfort, for some reason twitch uses Xsolla as it's payment processor. That is, you cannot pay for premium twitch with your amazon account.

That's just an alternative option. You get Xsolla if you click "more payment options". Amazon Pay is the default.

Agreed. Hopefully you will be correcting that.

Looks like passwords were hashed with bcrypt using a cost factor of 10. I wouldn't be too worried for people with good passwords set up even if hashes got leaked. People with common passwords should probably change their passwords just in case though.