Unfortunately, thats not quite how it works.
Changing the blend mode really only affects the ‘drawing’ – it doesnt change the alpha values or anything in the texture.
You might need to run a jit.gl.slab to change the texture from premultiplied to unpremultiplied (or, perhaps, vice versa).
You’d do something like.
jit.gl.slab (some slab shader here that does alpha changing)
(in short hand)
That could be helpful perhaps!