People are talking about British economic decline.

Not just the decline from bestriding the world in the 19th century to today. A more recent, more profound decline, starting in the early 2000s, when it fell off the track of normal developed-economy growth. See for example this graph from We Are In An Unprecedented Era Of UK Relative Macroeconomic Decline:

https://astralcodexten.substack.com/p/highlights-from-the-comments-on-british