There are many existing threads on this issue, so I’m surprised you didn’t see one already.
In any case, the answer is that Samsung has decided to stop selling and supporting home automation hardware. They will continue to provide the cloud and the app, but the devices will now be sold under the brand of partner companies. In the UK, this is Aeotec. They have released a new version of the hub which is the same as the V3 version, it just has a different logo.
Official announcement:
Amazon has been going in and out of stock on the new hub, here’s the product page:
https://www.amazon.co.uk/Aeotec-Smart-Home-Hub-version/dp/B08MXG6WTB