MacBook Air M3 Weird colored lines

First, let’s see if this issue happens in Safe Mode:

1. Shut down your Mac.
2. Press and hold the power button on your Mac. As you continue to hold the power button, your Mac turns on and loads startup options. When you see Options, release the power button.
3. Select your startup disk. It's named Macintosh HD, unless you changed its name.
4. Press and hold the Shift key, then click the “Continue in Safe Mode” button below your startup disk.
5. Log in to your Mac. You might be asked to log in again.

If the strange behaviors do not occur, then it may possibly be a software issue.

If the issue doesn't continue in safe mode:

Leave safe mode by restarting your Mac normally, then try to reproduce the issue.

If the issue doesn't return, it might have been resolved by the other things that safe mode did at startup, such as checking your disk and clearing caches.

If the problem persists, then let’s try this:

• Software Update.
• Use Apple Diagnostics to test your Mac.

If none of those ideas work, then I recommend service.

Service Checklist:

• Mac service pricing.
• Check AppleCare Coverage.
• Get your Mac ready for service.

Click ▶︎ Start a Service Request. ⚛️

Need more help?

• Call 1-800-APLCARE.
• International Support.
• Mac Support.
• Mac User Guide.

Click ▶︎ Check Repair Status. 🔧

Good luck! 👋🏼😉

As long as there are no signs of accidental damage, then it will likely be covered by the Apple one year product warranty. If there are signs of accidental damage, then most likely it will be a very expensive repair.

You need to have Apple or an Apple Authorized Service Provider examine the laptop to determine if the failure is covered by the product warranty. Only Apple can determine this and they always have the last word on the matter for warranty coverage.