I don't know what I'm talking about, I'm not a professional or even a great artist but there are certain things that show hints of Photoshop. The most obvious one is when you can see individual brushstrokes and you recognize the basic round brush.. Maybe the settings have been fiddled with, some texture added, opacity lowered.. But it still doesnt hide that the mark was made by a basic round brush.. Especially when there are 3 parallel strokes like I this detail:
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To take it to the next level maybe try experimenting with different brush shapes, or work in more detail with a smaller brush to get rid of the round brush shapes.
Again, take all this with a grain of salt because I probably have no idea what I'm talking about.