The contributions feature was launched over 8 years ago to give developers an easy way to receive compensation for their add-ons on AMO (addons.mozilla.org). This system relied on an integration with the PayPal API, which often caused problems. It didn’t work properly for users with restricted cookie settings, for instance. It also meant PayPal was the only payment provider.
We just launched a new contributions system that is simpler, more reliable, and flexible to use.
With the new system, developers specify a contributions URL in the Developer Hub. The Contribute button on their listing page will point to that URL and open it in a new tab. Initially, we will be supporting Patreon, PayPal, and Micropayment as payment providers. If you’re a developer and would like to propose other services for inclusion, please add your feedback to this forum thread.