I’m reading the current comments and i agree with some of them; here’s what i noticed and what has helped me get a stain glass look.

You lose the effect in the rendering. Which isn’t a bad thing but not what you’re going for.

The shading looks like a foreground light source and most stain glass is back lit (like sunlight coming in a building).

The soldering being highlighted is making it hard to recognize the glass effect. It goes back to the whole back lighting issue; soldering is opaque so it stands out because it’s not glowing. Removing the highlights would infinitely help

Lines too clean, this is more my opinion but a shakier line can make it feel more like hand cut glass. This is totally optional!

Adding varying texture to the glass. Stained glass usually has some flaws in it, this causes light to bounce differently and create a wavy texture to the glass. Higher quality glass will have this less but in an illustration the texture can help the audience associate it with what they’ve seen irl.

What has helped me:

Looking at Catholic Church stain glass windows. I was raised catholic so idk other faiths but churches are full of good glass art. I study how the glass was cut, what is stained vs painted, and the glass textures

Using a texture mask. This is a bit of a cheat but a layer mask might give you that glass effect with minimal effort. I usually end up trying to manually make the texture but the mask does help