Brush marks of Zinsser bin showing on wall.

Get 160 grit paper and sand lightly this will get the brush marks out then paint with 2coats of emulsion

Fill it out re pant

Rub down with 240 grit wet and dry (wet) and use a 4 inch roller to re apply subsequent coats. This will match the remaining rolled surface.

Sand the surface: Gently sand down the visible brush marks in the dried primer until the wall feels smooth to the touch. Re-prime if necessary: If sanding exposes the original stain, apply a thin, even coat of primer to those areas using a roller for a smoother finish than a brush. Apply topcoat: Once the primer is completely dry, apply your final paint coats, ensuring even coverage. Consider product usage: Zinsser BIN is a thin, fast-drying shellac-based primer that seals stains well but can show brush marks if applied too thickly.