Despite it being called, Incognito Mode in Google's Chrome browser, you are not truly in Incognito Mode.
There are some website developers that discovered a way to detect if a user is in this mode, or not. You can go and search for "how to detect incognito mode" and you will see a lot of tools that developers can use to check if users are in Incognito Mode. However, now it seems that Google has decided to fix that as seen in recent commits to Chromium's Gerrit source code management. So basically your Incognito Mode will now truly be Incognito.
Google's intention for this mode is to give you privacy, they do so by temporarily disconnecting you from all your logged in accounts that links back to Google as well as those from Facebook and even Amazon. But for the longest time, it has had a flaw that developers can overcome in order to determine if a user is using Incognito when visiting their website. Most sites make money from tracking and advertising, so they especially need the data captured by Google in order to do so.
Developers use a tool – which is one of the most popular methods right now, in order to try to access the Filesystem API. This API is disabled when users are in Incognito Mode, so if they cannot access that information, then the user is currently in an undetectable mode. Google's plan is to remove the FileSystem API altogether. This will then create a virtual file system using RAM when it is asked for a file system while in Incognito Mode.
This incognito detection prevention feature will only arrive with the Chrome 74 update but it will be behind a flag. Users who know how to enable the flag feature will be able to access the Incognito mode to its fullest extent, However, if you do not know how to do this, or if you prefer that it is automatically enabled, you'll have to wait for Chrome 76 to make an appearance.