Hi there,
the core Block widget doesn’t respect the Customizer colors – they only apply to the Theme Buttons.
If you want better styling control over a button in the editor then i would recommend using the GenerateBlocks plugin, which gives you full color controls for the button and other styling options:
https://docs.generateblocks.com/article/buttons-overview/
And if needed we can provide some Code so the GB Buttons do respect the customizer colors.