That comes with its own set of issues when google decides to block your account for reasons only known to their algorithms and there are no humans to talk to. You end up locked out of your business email with no recourse.
Smaller commercial email providers are probably a good balance of competence and reliability (their email service is their revenue source) and better customer service (they have few enough customers that they care more about each of them). Fastmail is often brought up in this category. I think Zoho is pretty good too if you're looking for more of a complete G-suite like offering with other applications. Both of these companies also increasingly feel like more competent or at least better-run software engineering organizations than Google.
Having your own domain you control the MX record. If google locks you out, you can still move to another host for your email on the same day. You don't get your historical email (unless you backed it up with offlineimap or something like that) but at least you still have access and control over the address. Using @gmail.com for your business (or even personal email) is asking for trouble given how notorious google is at locking people out with no recourse and for mysterious reasons.
