useForm - Why only an empty array [] would work for empty value in a form submissions?

[erip2]

Firstly, sorry if the answer is not that clear, my back-end vocabulary is not rich.

This may be a question related to JS, not your library, but I want to be clear, because it is a bit confusing to me.

So, I have a filter form, let's say it's like this:

const form = useForm({
    email: props.filters.email ?? '',
    name: props.filters.name ?? '',
    budgets: props.filters.budgets ?? null,
    type: props.filters.type ?? '',
    campaign: props.filters.campaign ?? null,
    source: props.filters.source ?? null,
});

The type of campaign and source is a checkbox.

If I use that form and submit it, the filter doesn't work and this how this data is shown on back-end. I'm showing the $request->all() object:

"bride_email" => null
"name" => "Test"
"budgets" => null
"type" => null
"campaign" => null
"source" => null

and the filtering is not correct. It's alway empty data.

But, if I change in the useForm from null to [], this is the result:

"bride_email" => null
"name" => "Test"
"type" => null

The check-boxes are not shown at all (as they should) and the filter works normally.

So, if anyone could explain what is the reason for this?

Thanks!