Even if the snapshot button is not ticked, "Latest snapshot" can still be selected next to the Play button. While this isn't exactly critical, this means that no warning is shown, and new users may accidentally corrupt worlds, and I (if I remember correctly) believe that the world warning was recently disabled too.

I found similar issues, but none of them seemed to be exactly the same and are already marked as resolved.

Not tested, but this should be the case on Windows and OSX, since the Linux version seems to be more up-to-date than it used to be.