The specification states that the timestamp property is a DOMHighResTimeStamp which always represents a value in milliseconds. However, in my testing (on iOS as I don't have a mac) the timestamp is given as seconds. This could break compatibility if an app/library is not tested in Safari. Worse is that the deviation seems to be undocumented as every compatibility chart states full compatibility and defines the property as milliseconds. Any workaround would also be up to one frame incorrect. So a stutter can affect input accuracy. I know this might seem small but it could mean that an app or game is unplayable in Safari if it relies on this for input.