Why is this transparent?

The text is opaque, it just needs to be moved above the paint layer.

Because the color splash group is set to "Multiply" it is darkening the gray text. If the text was a "rich black", like the paint brush, the color difference would not be visible.

The link requests "access permission".

Just some guesses:

Check the "opacity" setting on the fill color. This is accessible from the "Transparency" or "Appearance" panels.

"Brushes" are controlled by the "Stroke" color. If you're using a predefined art brush the brush artwork itself may have transparency assigned to it. You would need to choose a different brush pattern, edit the brush artwork (by dragging it onto the artboard) or creating your own custom brush.