This is an issue that has been raised in various forms on various occasions, including by myself.
I feel Monzo’s security posture is very deficient as it totally depends on the security of the device, the registered email, and some ridiculous “security questions” which are quite simply useless.
Sadly, this is something that Monzo see differently and I have come to the conclusion that if I do t share Monzo’s views in this matter, than I must take my custom elsewhere…