What's Bad About WhatsApp
Data Collection
It is no wonder that WhatsApp collect data, it is owned by Meta! WhatsApp? You mean WhatsTrack! All of the data collected is sent through Meta/Facebook. That means your data gets sent to one of the largest advertising company there is.
Ethics
First of all, if you report something illegal on WhatsTrack, they will probably take no action. They do not care if you send bomb plans or a shopping list to your friend, because every message and every collected metric is making them money.
The client is not Open Source
It requires a phone number (which can be easily trackable) for signing up. Although many platforms require a phone number, WhatsTrack will probably store that data and use it for advertising.