Prior to Chrome 76, the FileSystem API was disabled by default in Incognito Mode, and websites started tracking the API to determine whether the user was browsing normally or not. Now, Chrome makes the FileSystem API available in Incognito Mode as well, thus closing the loophole.
However, developer Jesse Li just discovered that, although the FileSystem API is used in Incognito Mode, Chrome stores data written to the API in memory instead of saving it to disk. He says: “when we choose to use memory, we make some tradeoffs: RAM is temporary storage, making it an attractive medium for incognito. But side effects include smaller space and higher speed than disk,”.
This does not resolve the issue where websites can detect whether Incognito Mode is in use, thus delivering a different experience to users.