> I am curious if it is because they care slightly less if it's a CA VOIP number, if it came from a decent pool of numbers, or something else. Or if they will lock you out later and force you to contact the "risk assessment" team and use this as a datapoint.

Interestingly it's an old landline number that got ported over to voip.ms, so you'd expect that if it were trusted due to reputation, it'd also only be accepted as a landline. Yet the validation experience has no problem with it.