[tellyblues]

According to Ofcom: The quotas in Channel 4’s current licence are for at least 56% of programmes broadcast each year to be original productions overall and, in peak viewing times, 70% of programmes to be original productions

If that's from www.ofcom.org.uk  (published Dec 2023), at 5.66 on page 47; The channels can use repeats of their content to fulfil this quota, meaning that the quota does not guarantee the broadcast of first-run original productions.

Other channels operate under similar terms. BBC Scotland has a requirement to show original programming but original just means commissioned at any time for the channel. They could just repeat what they've got and add the other requirement of news and nobody can do anything but moan about repeats.