Why the length of EventTouch's _touches changes

when i use the EventType.TOUCH_START,i use two fingers at the same time, i found that:

on IOS platform,(iphone 13, safari), the length of EventTouch._touches is not always the same, 1 or 2

on Andriod platform,(Remdi K30 Pro, chrome).the length of EventTouch._touches is always 1
Sorry for that new comer can only upload one media file,the _touches are both _touches: [216.cc.Touch]

Does someone know the reason?

which version of creator you are using now?

2.4.7