There’s IBB; the internet Bug Bounty. But it’s for widespread open source software. Typically FOSS that isn’t well funded yet is critical to massive parts of the internet. Popular libraries, email & DNS infrastructure etc.

Ebay being a private company with boatloads of money is definitely not a part of that.

Its more for things that affect an OS or browser I thought but I could be misremembering, project zero or whatever is relevant to their efforts in securing software.