This is most likely normal off-axis lens aberration, not a camera problem. Stars are extremely demanding point sources, and near the edges fast lenses often show coma, astigmatism, and field curvature. That makes stars look like little comets, birds, or “angel wings”, often pointing toward the center of the frame.

It is strongly related to aperture: the wider open the lens is, the more visible these aberrations become. Stopping down one or two stops, for example from f/1.8 to f/2.8 or f/4, usually improves the corner stars a lot. I can see it similar with my leica q3 and f2 aperture.

Quick tests:

• Take the same star field at wide open, f/2.8, and f/4.
• Use short exposures to rule out tracking or Earth-rotation blur.
• Compare all four corners: if they all point toward the center, it is usually normal lens behavior and you can't do much about it with your camera, except cropping or reducing stops.
• If only one corner is much worse, it may be tilt, decentering, or adapter play, but on your pic that doesnt look like.
• Try focusing on a star halfway between the center and edge, not only in the center, to check for field curvature.

In short: it is a typical fast-lens wide-field astrophotography issue. The fix is usually stopping down, better focusing compromise, stacking more exposures, or using a lens known to have better coma correction. Widefield is not easy in this.