Probably a stupid and obvious question but...

LND returns pre-images that look like:

3KKpToqROgTCoOun1xnEvdr7QrzQKKJ05Kh3WOK0yVE=

But on Zeus I see them looking like:

b9da4a7cb7ace18070d328d9b10803579ec61a5750778dcb6436763976058b01

Two questions:

1) is this is a sha256 hash of the pre-image?

2) why bother hashing it, is this sensitive after it's already been paid?