Complaining, comparing, and criticizing are necessary for improvement. This is the main responsibility of bosses.
But good bosses also allow their subordinates to criticize them.
I firmly feel that too many Christians go too far in humility and meekness, where it ceases to become a virtue.
Much of this, by the way, is related to the personality type called “agreeableness”, which is determined (primarily) by genetics and in childhood, which no one can be blamed for.
Furthermore, people who are disagreeable, rarely make personal attacks because they are focused on results, and not people. I see no sin to criticize results in most cases.
I would suggest you try to go one complete day without complaining, comparing or criticizing others.
Then at the end of the day, examine your conscience and see how you did.
I bet you will feel better than you expected.
BTW, a good boss will get better results with compliments toward an employee that with the three Cs.