I like SonarQube for removing ambiguity. If SonarQube is set to fail the build at lower than a certain percentage of coverage or too low of a grade in Maintenance then it gets fixed before the PR even gets filed.
Assuming the code is processed by SonarQube for regular branch builds, which it should be.
The word "must" should only be used in the Military. Anywhere else, it is profusely out of place. In its stead, I recommend the term "requirement" and then cite an actual reference by the PO or someone officially representing the business requirements.
I agree with "Don't defend a point to win an argument or double-down on a mistake.". I disagree with the juxtaposition that ego is bad, i.e. "no ego". Ego is defined by Oxford as "a person's sense of self-esteem or self-importance.", I agree.
Ego isn't bad. To use it in a context directly indicating it's bad is wrong. If the world agrees to do away with the word ego then it must be replaced by something that also means "a person's sense of self-esteem or self-importance.".
A coder without any ego is a coder who doesn't care, at all, about anything.
Assuming the code is processed by SonarQube for regular branch builds, which it should be.