This is most likely a lens issue, not a general “mirrorless cameras are blurry at the edges” problem.

If you were using the Sony 16-50mm power zoom kit lens (SELP1650), it is known to trade edge sharpness for compact size, especially at the widest setting. That can make corners and outer areas look softer than the center.

Your sample may also show one of these additional issues:

• decentering: one side is softer than the other, suggesting a misaligned lens sample
• field curvature: the plane of best focus bends, so edges can be out of focus even when the center is sharp
• subject movement: some doubled detail can look like motion blur rather than optical blur

Some mirrorless cameras can show edge problems with certain adapted wide-angle lenses because of how light hits the sensor, but that is a different issue. It does not mean entry-level mirrorless bodies in general are flawed.

So the likely explanation is the specific kit lens design, and possibly a bad copy, rather than the A6000 body itself.