Memory tagging exception(or "error") happens when you have faulty low-level code in your app, probably a type of pointer mismanagement.
It could be an attack.. But some apps' code just sucks, that the default state is tripping the memory tagging exception. WhatsApp is known to be one of those apps. You probably have to disable MTE and maybe one or more security settings. And if there's an attack, it should reasonably remain within the confines of taking control of WhatsApp i.e. the attacker will have same access and abilities as WhatsApp.
If you want to keep using WhatsApp and keep a higher level of seperation, you can use a seperate user just for WhatsApp. It will not increase your protection, but when WhatsApp is hacked or decides to act out against your interests, it will be fully isolated from your main user.
Oh and also, sometimes you may not get notification that the MTE is getting tripped; do keep in mind that, it might be the reason why a specific app crashes.
