FUNDING.yml preference not respected

Update: I think it makes more sense to discuss if we should maybe just use the first FUNDING entry, asking developers to put what they prefer on top. That seems more sensible to me than always preferring custom. I have thus changed the issue.

I noticed that Catima only shows PayPal, despite the FUNDING.yml also containing GitHub Sponsors:

github: TheLastProject
custom:
  - "https://paypal.me/sylviavanos"

Creating this issue on fdroidserver as it is displayed without GitHub Sponsors on both the website and the client.