Ventura- Display corruption on 5120x1440 display

Hello SteveTee22,

Welcome to Apple Support Communities!

We want to make sure displays are working normally after the update to Ventura.

Let's confirm you took these steps for an issue with the external display:

"If your display appears blurry

If images or text on your display appear blurry or pixelated, check the resolution and brightness of your display.

Adjust the resolution

1. From the Apple menu, choose System Preferences, then click Displays.
2. In Display Settings, select the external display in the sidebar, then press and hold the Option key while you click Scaled to see additional resolutions.
3. Select a resolution, then click Done.

If the expected resolution doesn't appear for your display, check the specifications page to see what display resolutions your Mac supports."

This Apple Support page has the full details and more steps to take: If your external display isn't detected or appears blurry when connected to your Mac - Apple Support

You might also check for any updates to your monitor. We hope this helps to resolve the issue and get the display looking great again.

Cheers!

These steps won't resolve the issue as it's nothing related to settings or a particular machine. I've just encountered it myself after my macOS was updated to Ventura last week. And a second MacBook on BigSur was working fine until it too was updated yesterday and no longer working for the same monitor. Apple needs to release OS update to fix this.

For @SteveTee22, You can temporary work around with PBP/PIP to make use of the display as two separate monitors (one connected with USB-C and another with HDMI) but you won't be able to make use of whole 5K display as a single unit.