Recently I found with this issue on Livewire when I add an property to a wire:model as an array of ids it automatically transform the content into integers.
$this->roles = [1,4,5];
After clicking on the checkboxes it become something like this:
$this->roles = [1,4,5,"1"];
Here is a better explaining about this: https://github.com/livewire/livewire/issues/1354
So the proposed solution on this thread is to put on the assignation something like this:
$this->roles = array_map('strval', [1,4,5] );
In order to have the values as strings instead of integers.