What you’re seeing is likely a mix of normal night-sky capture limitations rather than a camera fault.

• Odd star colors: Stars are tiny point sources, often landing on only a few sensor pixels. Because the sensor records color through red/green/blue filtered pixels, very small points can show exaggerated or shifted colors. High ISO noise can make this more obvious, and lens chromatic aberration can add colored fringes around small bright points.
• Blotchy/uneven sky color: This is consistent with light pollution, often made patchy by dust or haze in the atmosphere reflecting nearby city light.

To reduce it:

• Shoot from a darker location with less light pollution.
• Choose clearer air with less dust/haze.
• Use the lowest ISO and longest exposure that still gives the result you want without unacceptable star trailing.
• If possible, shoot RAW for better control over noise reduction, white balance, and color cleanup.
• Check for and minimize lens aberrations if visible around stars.

Some color variation in stars at 100% is normal in high-ISO night images, especially in JPEGs.