The '6' in a partial square stamp on left front trigger means 1946.
'A' serials started in late '44 after liberation in Sept.,
and were (mostly) used until early '46.
Then serials started over at (000)1 in '46.
The 1922 serials began at 200,000 and went to ~280,000, before the Germans took over in 1940 - with their own set of proofs and serial ranges.
[There were also many contract guns made 1922-1940 for other countries militaries and police, with their own serial ranges].
It's common for vendors to list an "early pre-war" FN1922 because
the serial is below 50,000 or so and has Belgian proofs.
BUT these are invariably post war 1946 guns, marked like yours (without the 'A' prefix though).
Short version: if a Belgian proofed FN1922 has a serial below 200,000 - it's post-WWII.