Monzo is my main bank where my salary comes in, my purchases are made and my bills come out.

It works great and unless they start going South I wouldn't look back.

I don't know but I started using Monzo as a more convenient alternative to Barclays and as Monzo added features (and Barclays didn't) I switched my pay to go into Monzo. It's nor particularly hard to email your employer and let them know some new bank details, and the Barclays experience (particularly their slow balance updates) makes it easy to want to use something different.