I was configuring my M5 MBP preorder and 48=>64 was 250 EUR so not sure if they cut prices or your numbers are outdated ?
I just did a 14" MBP with M5 Max, 128GB RAM, 4TB SSD, nano-texture display. Price difference is $5849 vs 7004 EUR ($8136).
But my point is that's a 16GB jump for 200$ not 8GB
14' MBP M5 Pro 64GB - $2999 or 3449 €