I make 54k net in Romania working as a backend developer. If I move to France and use C++ my living standard would take a hit. :D

Those job ads are both better than my current position. £40k for cross-platform C++ desktop app with both multi-core and distributed parallelism. PhD required. GPGPU experience preferred (notice that it's not CUDA experience because some users have AMD cards). Now, with two consecutive promotions, I could bump my salary up to £50k. Of course, to qualify for the second of those promotions, I need to receive personal commendations from three different professional organizations across at least two different countries.

I feel your pain, I've been there.

My advice, get a job around (but not in) London area, if not, get a remote role with a company in south, that gave me a bump from 35k to 71k.

Even better, leave perm and get a contract (outside IR35), you can easily get between 350 to 450 a day.

... and yes, that's doing C++, some Qt, some MFC, some Python, and no PhD/MSc nonsense.