I think it would be safe to remove the bulk verification function from this.

I have built this same project with Whatsapp Web and have played with this approach to it's limits.

Whatsapp Web has started to count the number of Whatsapp Web requests you are making and if it exceeds a threshold they will just block your number with no support to reach to.

This feature was heavily abused in Indian general assembly elections and led to a lot of spam alerting Whatsapp to setup checks on this.

Would recommend adding a cautionary note.