Tested versions

Godot 4.2 (mono)
With GD Script

System information

Windows 10 64 bit ryzen 5600. Godot 4.2.1 stable mono official b09f793

Issue description

I have a 64 bit integer I print the value of. It is the correct value.
my number is in the "quadrillions." (5 commas)
When I set the value, it changes to a number in the millions.

Steps to reproduce

Using GD Script

# Example number with commas : 12,345,678,901,234,567
var my_id : int = 12345678901234567

print("My number is : " + str(my_id) )
my_other_node.set_multiplayer_authority(my_id)
print ( "Is my number the same? " + str(my_other_node.get_multiplayer_authority) )

Minimal reproduction project (MRP)

As far as I'm aware this is all you need.
I'm not using Godot's multiplayer API for anything. I WAS using that. The steps to reproduce should be capable of showing you the problem.