Really? The UK left more than a year ago. There was merely a transition period where they would abide by EU regulation.

Only for one clause of the contract. There's a requirement that all vaccines supplied under the contract are sourced from within the EU, with some provision for AstraZeneca to source from elsewhere under exceptional circumstances, and it says the UK is treated as part of the EU for the purpose of that clause and only that one. The part requiring them to set up an EU supply chain and make a best effort to supply the EU with a certain number of doses on a certain schedule does not include the UK. Like, someone went to actual effort to ensure it didn't apply to that part of the contract (and I wouldn't be surprised if it came from the EU side).

Yep, the contract between the EU and AZ explicitly states that the UK shall be treated for most purposes (manufacturing site and so on) as an EU member. The UK is not included in the EU orders so.