Hi!

One of my batteries doesn't look good. Still works but it doesn't feel safe flying when it looks like that.

Recycle? Warranty? How would one continue in this situation?

"Puffed" battery...Do not use.  If it's covered under warranty contact DJI asap.

Contact support, it looks like a fault with the battery - and it should be replaced ASAP.

Agreed don’t use it.

Typically this happens by keeping the battery fully charged.