render.OverrideBlend misbehave under Linux

[DBotThePony]

Details

I am not able to make minimal reproduce code yet, but it really misbehave in my render case (2D rendering (HUD))

This is what i get under Linux (i use OverrideBlend and stencils to make mask for scanlines and distortion effect)

And it should render like this (Windows)

(and yet again, i have to find workaround for https://github.com/Facepunch/garrysmod-issues/issues/415)

Blend call in question: render.OverrideBlend(true, BLEND_SRC_ALPHA, BLEND_SRC_ALPHA, BLENDFUNC_ADD, BLEND_ZERO, BLEND_ONE, BLENDFUNC_ADD)

HUD is getting rendered onto render target (to apply some visual effects, which are impossible to do with regular rendering directly to main render target), then after manipulations it is being rendered onto main render target

[robotboy655]

I don't see anything wrong besides the font (and the size?).

[CornerPin]

I suppose the issue is the background being rendered. Here I adjusted the contrast to make it more visible. Linux: Windows: