if ('storage' in navigator && 'estimate' in navigator.storage) {
const {usage, quota} = await navigator.storage.estimate();
console.log(`Using ${usage} out of ${quota} bytes.`);
if(quota < 120000000){
console.log('Incognito')
} else {
console.log('Not Incognito')
}
} else {
console.log('Can not detect')
}
see : https://mishravikas.com/articles/2019-07/bypassing-anti-incognito-detection-google-chrome.html