how to make star-shaped circle into a regular circle plane So i have this model

As you can see there is a rust texture on top of it, but it is messed up because the circle (after subsurf) that is on top of it is being inverted by some sort of star shape, after removing the face and adding a circular plane, i discovered that there are a bunch of triangles inside the outline of the shape. I would like the texture to be properly shown on top of the barrel and for there to not be a bunch of triangles around the circle
I'd try to use something like rectangles instead of single N-gon. Like this:


Just delete face only, select the outer edge, press E to extrude, right click to cancel moving, S to scale almost to the center. then use Ctrl+R to add few edge loops, and fill the center. It will subdivide more consistently. And fix duplicating faces (flickering ones) to avoid problems on rendering.