syncWithoutDetaching is throwing an integrity constraint violation, allows unlisted arguments

[drewgallagher]

We are using syncWithoutDetaching with a table called strategy_department which has a unique constraint on a primary key with strategy_id and department_id having to be unique.

Laravel allows us to pass a single arg like an id (i.e. 1001), however the docs don't list that as an option https://laravel.com/api/8.x/Illuminate/Database/Eloquent/Relations/BelongsToMany.html#method_syncWithoutDetaching. There are no errors thrown.

However we see an on and off integrity constraint when using it this way. Is there an error with syncWithDetaching with a single id passed as an arg that doesn't allows work?

Sample code

$strategy_package->strategy()->first()->departments()->syncWithoutDetaching($task->service->department->id);

We are triggering a graphql endpoint with this code with several different requests (that could have the same department id).

Is there an issue running this call in parallel?

$strategy_package->strategy()->first()->departments()->sync($task->service->department->id, false);
appears to be working correctly, not sure why one would produce a result that the other would not

We are using V8 of Laravel