Hello,

I saw the screenshot you attached. Please try adding the following Custom CSS in the Global Custom CSS area under Theme Settings >> Custom CSS.

.whb-color-light .search-style-default input[type=text] {
    color: black;
}

.whb-color-light .search-style-default input[type=text]::placeholder {
    color: black;
}

Regards.
Xtemos Studios.