odoo18/addons/web/static/src/scss/ace.scss

.ace_editor .ace_qweb {
    color: orange !important;
}
.ace_editor .ace_code {
    color: fuchsia !important;
}
.ace_editor.ace-monokai .ace_qweb {
    color: lightblue !important;
}
.ace_editor.ace-monokai .ace_code {
    color: #c94bc9 !important;
}