While the Tab Groups feature is pretty useful to a lot of users on desktop, the Chrome for Android version leaves a lot to be desired. It's not as intuitive as the desktop version and a lot of users have been requesting to disable this feature by filing bug reports. Google has responded to this by saying that they are experimenting with bringing changes to the mobile version based on how people are using it and the feedback they have received from users.

Link: Chrome for Android making changes to Tab Groups
via androidcommunity.com