My mac screen becoming green

Does it briefly do this during startup, or does it stay green?

ColorSync Utility User Guide for Mac - Apple Support

is a good guide for Ventura.

Apple menu -> System Preferences -> Displays -> Color on earlier Mac OS versions lets you manage the overall color on Macs.

If neither gets rid of the tone, you may have a graphics issue with your computer. Call AppleCare to have your computer serviced. Backup your data before bringing/sending it in.

A screen that's off color enough to be noted is likely a failing graphics card. But with no details, that can't be known for sure.

Please read this post and restate your issue using the points in it to help you: Writing an effective Apple Support Commun… - Apple Community

If you screen or graphics card is failing, that must be handled hands-on by Apple.