Gray and grey are two spellings of the same noun, adjective, or verb. The spelling depends on the type of English:
In American English, you use “gray,” so grayed out is correct.
In British English, you use “grey,” so greyed out is correct.
The adjective grayed out or grayed out refers to something like a menu item or button on a computer screen that’s not highlighted, indicating that it’s inactive.
It’s important to choose one spelling and use it consistently. The QuillBot Grammar Checker can help you with this