Why does the number of XPath change?

I have an input that is changed by many factors.

Therefore, this input will be accessed from different paths. However, one input has multiple TestObjects because each access path changes the number value of XPath.

//*[@id="mat-input-3"] //*[@id="mat-input-4"] //*[@id="mat-input-15]

These Selected Locators (XPaths) point to one input.

Can’t this input have one TestObject?

When not only input but also other HTML elements approach the path differently, the number value of XPath seems to change. What is this number value?