Horizontal red lines at top & bottom of screen when streaming Netflix on MacBook Air!

Hello MsCymon,

Welcome to Apple Support Communities. It looks like you see red lines when you stream content from Netflix on your Mac. We understand your concern with your behavior, and we'd be happy to look into this with you.

Are you using Google Chrome, Mozilla Firefox, Opera, or the Safari browser when you stream Netflix on your Mac? Does the issue persists if you tried again using a different browser? When did you first notice this behavior? Do you recall anything changing on your Mac around the time this issue started?

To get started, let's try to test in another user account on your Mac. Here's how to create one:

Set up users, guests, and groups on Mac

We hope this information is useful. Kind regards.

Hello MsCymon,

Thanks for getting back to us with those additional details. We understand having red bands when streaming Netflix using Safari on your Mac. Let's continue working on this together.

When an issue doesn’t happen in a new test user, that means that a setting or a file in your original account might be causing issues.

To get started, let’s check your login items which are user specific to see if the issue may lie there. From the Apple menu > System Preferences > Users & Groups > Login Items. Let’s take note of and then remove any items you see there.

Now, we’d like you to test without any login items and then add them back one at a time.

Also, you can try the steps in the following link:

Clear your browsing history in Safari on Mac

Let us know what you find and we’ll continue together. Cheers!