> For instance recently I made a small change to a table and a coworker pointed out that there was a microservice I wasn't considering that wrote to that table that would break

If code reviews are important, where does testing sit? Presumably if the coworker had not been part of the code review something would have stopped the breaking change making its way to prod?

> something would have stopped the breaking change making its way to prod?

or a prod outage causes the knowledge to be experienced.

I'd guess testing is done only for the software being deployed, not for that other microservice.

At least, that's what people do by default.