You can still get quad cores, here's an Epyc CPU with four cores [0]

Here's also a recent Xeon quad core [1]

Beside that, could you please show me where the F-Droid build server uses an Oracle Database?

[0] https://www.amd.com/en/products/processors/server/epyc/4004-... [1] https://www.intel.de/content/www/de/de/products/sku/236193/i...