For a Western country the UK is actually doing alright - closer in median age to North America than Central Europe, and probably has the strongest migration prospects of non-colonial Western countries.

Eh? The UK's problems are pretty typical of a developed country; aging population. The Russian problem is something else entirely. You'd definitely want to have the UK's population challenges over Russia's.

Yes the UK in the same (if not slightly better) position than most other "developed" countries.

However, the green account tells me the the actual intention of the comment is about the "Great Replacement" or other such conspiratorial nonsense.